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linux/fs/btrfs/file.c
Filipe Manana 7ee85f5515 btrfs: fix race setting file private on concurrent lseek using same fd 
When doing concurrent lseek(2) system calls against the same file
descriptor, using multiple threads belonging to the same process, we have
a short time window where a race happens and can result in a memory leak.

The race happens like this:

1) A program opens a file descriptor for a file and then spawns two
   threads (with the pthreads library for example), lets call them
   task A and task B;

2) Task A calls lseek with SEEK_DATA or SEEK_HOLE and ends up at
   file.c:find_desired_extent() while holding a read lock on the inode;

3) At the start of find_desired_extent(), it extracts the file's
   private_data pointer into a local variable named 'private', which has
   a value of NULL;

4) Task B also calls lseek with SEEK_DATA or SEEK_HOLE, locks the inode
   in shared mode and enters file.c:find_desired_extent(), where it also
   extracts file->private_data into its local variable 'private', which
   has a NULL value;

5) Because it saw a NULL file private, task A allocates a private
   structure and assigns to the file structure;

6) Task B also saw a NULL file private so it also allocates its own file
   private and then assigns it to the same file structure, since both
   tasks are using the same file descriptor.

   At this point we leak the private structure allocated by task A.

Besides the memory leak, there's also the detail that both tasks end up
using the same cached state record in the private structure (struct
btrfs_file_private::llseek_cached_state), which can result in a
use-after-free problem since one task can free it while the other is
still using it (only one task took a reference count on it). Also, sharing
the cached state is not a good idea since it could result in incorrect
results in the future - right now it should not be a problem because it
end ups being used only in extent-io-tree.c:count_range_bits() where we do
range validation before using the cached state.

Fix this by protecting the private assignment and check of a file while
holding the inode's spinlock and keep track of the task that allocated
the private, so that it's used only by that task in order to prevent
user-after-free issues with the cached state record as well as potentially
using it incorrectly in the future.

Fixes: 3c32c7212f ("btrfs: use cached state when looking for delalloc ranges with lseek")
CC: stable@vger.kernel.org # 6.6+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-17 17:31:48 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/falloc.h>
#include <linux/writeback.h>
#include <linux/compat.h>
#include <linux/slab.h>
#include <linux/btrfs.h>
#include <linux/uio.h>
#include <linux/iversion.h>
#include <linux/fsverity.h>
#include "ctree.h"
#include "direct-io.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "tree-log.h"
#include "locking.h"
#include "qgroup.h"
#include "compression.h"
#include "delalloc-space.h"
#include "reflink.h"
#include "subpage.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#include "file-item.h"
#include "ioctl.h"
#include "file.h"
#include "super.h"
/* simple helper to fault in pages and copy. This should go away
* and be replaced with calls into generic code.
*/
static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
struct page **prepared_pages,
struct iov_iter *i)
{
size_t copied = 0;
size_t total_copied = 0;
int pg = 0;
int offset = offset_in_page(pos);
while (write_bytes > 0) {
size_t count = min_t(size_t,
PAGE_SIZE - offset, write_bytes);
struct page *page = prepared_pages[pg];
/*
* Copy data from userspace to the current page
*/
copied = copy_page_from_iter_atomic(page, offset, count, i);
/* Flush processor's dcache for this page */
flush_dcache_page(page);
/*
* if we get a partial write, we can end up with
* partially up to date pages. These add
* a lot of complexity, so make sure they don't
* happen by forcing this copy to be retried.
*
* The rest of the btrfs_file_write code will fall
* back to page at a time copies after we return 0.
*/
if (unlikely(copied < count)) {
if (!PageUptodate(page)) {
iov_iter_revert(i, copied);
copied = 0;
}
if (!copied)
break;
}
write_bytes -= copied;
total_copied += copied;
offset += copied;
if (offset == PAGE_SIZE) {
pg++;
offset = 0;
}
}
return total_copied;
}
/*
* unlocks pages after btrfs_file_write is done with them
*/
static void btrfs_drop_pages(struct btrfs_fs_info *fs_info,
struct page **pages, size_t num_pages,
u64 pos, u64 copied)
{
size_t i;
u64 block_start = round_down(pos, fs_info->sectorsize);
u64 block_len = round_up(pos + copied, fs_info->sectorsize) - block_start;
ASSERT(block_len <= U32_MAX);
for (i = 0; i < num_pages; i++) {
/* page checked is some magic around finding pages that
* have been modified without going through btrfs_set_page_dirty
* clear it here. There should be no need to mark the pages
* accessed as prepare_pages should have marked them accessed
* in prepare_pages via find_or_create_page()
*/
btrfs_folio_clamp_clear_checked(fs_info, page_folio(pages[i]),
block_start, block_len);
unlock_page(pages[i]);
put_page(pages[i]);
}
}
/*
* After btrfs_copy_from_user(), update the following things for delalloc:
* - Mark newly dirtied pages as DELALLOC in the io tree.
* Used to advise which range is to be written back.
* - Mark modified pages as Uptodate/Dirty and not needing COW fixup
* - Update inode size for past EOF write
*/
int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
size_t num_pages, loff_t pos, size_t write_bytes,
struct extent_state **cached, bool noreserve)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
int ret = 0;
int i;
u64 num_bytes;
u64 start_pos;
u64 end_of_last_block;
u64 end_pos = pos + write_bytes;
loff_t isize = i_size_read(&inode->vfs_inode);
unsigned int extra_bits = 0;
if (write_bytes == 0)
return 0;
if (noreserve)
extra_bits |= EXTENT_NORESERVE;
start_pos = round_down(pos, fs_info->sectorsize);
num_bytes = round_up(write_bytes + pos - start_pos,
fs_info->sectorsize);
ASSERT(num_bytes <= U32_MAX);
end_of_last_block = start_pos + num_bytes - 1;
/*
* The pages may have already been dirty, clear out old accounting so
* we can set things up properly
*/
clear_extent_bit(&inode->io_tree, start_pos, end_of_last_block,
EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
cached);
ret = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
extra_bits, cached);
if (ret)
return ret;
for (i = 0; i < num_pages; i++) {
struct page *p = pages[i];
btrfs_folio_clamp_set_uptodate(fs_info, page_folio(p),
start_pos, num_bytes);
btrfs_folio_clamp_clear_checked(fs_info, page_folio(p),
start_pos, num_bytes);
btrfs_folio_clamp_set_dirty(fs_info, page_folio(p),
start_pos, num_bytes);
}
/*
* we've only changed i_size in ram, and we haven't updated
* the disk i_size. There is no need to log the inode
* at this time.
*/
if (end_pos > isize)
i_size_write(&inode->vfs_inode, end_pos);
return 0;
}
/*
* this is very complex, but the basic idea is to drop all extents
* in the range start - end. hint_block is filled in with a block number
* that would be a good hint to the block allocator for this file.
*
* If an extent intersects the range but is not entirely inside the range
* it is either truncated or split. Anything entirely inside the range
* is deleted from the tree.
*
* Note: the VFS' inode number of bytes is not updated, it's up to the caller
* to deal with that. We set the field 'bytes_found' of the arguments structure
* with the number of allocated bytes found in the target range, so that the
* caller can update the inode's number of bytes in an atomic way when
* replacing extents in a range to avoid races with stat(2).
*/
int btrfs_drop_extents(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_inode *inode,
struct btrfs_drop_extents_args *args)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *leaf;
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
struct btrfs_key new_key;
u64 ino = btrfs_ino(inode);
u64 search_start = args->start;
u64 disk_bytenr = 0;
u64 num_bytes = 0;
u64 extent_offset = 0;
u64 extent_end = 0;
u64 last_end = args->start;
int del_nr = 0;
int del_slot = 0;
int extent_type;
int recow;
int ret;
int modify_tree = -1;
int update_refs;
int found = 0;
struct btrfs_path *path = args->path;
args->bytes_found = 0;
args->extent_inserted = false;
/* Must always have a path if ->replace_extent is true */
ASSERT(!(args->replace_extent && !args->path));
if (!path) {
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
}
if (args->drop_cache)
btrfs_drop_extent_map_range(inode, args->start, args->end - 1, false);
if (args->start >= inode->disk_i_size && !args->replace_extent)
modify_tree = 0;
update_refs = (btrfs_root_id(root) != BTRFS_TREE_LOG_OBJECTID);
while (1) {
recow = 0;
ret = btrfs_lookup_file_extent(trans, root, path, ino,
search_start, modify_tree);
if (ret < 0)
break;
if (ret > 0 && path->slots[0] > 0 && search_start == args->start) {
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
if (key.objectid == ino &&
key.type == BTRFS_EXTENT_DATA_KEY)
path->slots[0]--;
}
ret = 0;
next_slot:
leaf = path->nodes[0];
if (path->slots[0] >= btrfs_header_nritems(leaf)) {
BUG_ON(del_nr > 0);
ret = btrfs_next_leaf(root, path);
if (ret < 0)
break;
if (ret > 0) {
ret = 0;
break;
}
leaf = path->nodes[0];
recow = 1;
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid > ino)
break;
if (WARN_ON_ONCE(key.objectid < ino) ||
key.type < BTRFS_EXTENT_DATA_KEY) {
ASSERT(del_nr == 0);
path->slots[0]++;
goto next_slot;
}
if (key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= args->end)
break;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
extent_type = btrfs_file_extent_type(leaf, fi);
if (extent_type == BTRFS_FILE_EXTENT_REG ||
extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
extent_offset = btrfs_file_extent_offset(leaf, fi);
extent_end = key.offset +
btrfs_file_extent_num_bytes(leaf, fi);
} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
extent_end = key.offset +
btrfs_file_extent_ram_bytes(leaf, fi);
} else {
/* can't happen */
BUG();
}
/*
* Don't skip extent items representing 0 byte lengths. They
* used to be created (bug) if while punching holes we hit
* -ENOSPC condition. So if we find one here, just ensure we
* delete it, otherwise we would insert a new file extent item
* with the same key (offset) as that 0 bytes length file
* extent item in the call to setup_items_for_insert() later
* in this function.
*/
if (extent_end == key.offset && extent_end >= search_start) {
last_end = extent_end;
goto delete_extent_item;
}
if (extent_end <= search_start) {
path->slots[0]++;
goto next_slot;
}
found = 1;
search_start = max(key.offset, args->start);
if (recow || !modify_tree) {
modify_tree = -1;
btrfs_release_path(path);
continue;
}
/*
* | - range to drop - |
* | -------- extent -------- |
*/
if (args->start > key.offset && args->end < extent_end) {
BUG_ON(del_nr > 0);
if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
ret = -EOPNOTSUPP;
break;
}
memcpy(&new_key, &key, sizeof(new_key));
new_key.offset = args->start;
ret = btrfs_duplicate_item(trans, root, path,
&new_key);
if (ret == -EAGAIN) {
btrfs_release_path(path);
continue;
}
if (ret < 0)
break;
leaf = path->nodes[0];
fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
struct btrfs_file_extent_item);
btrfs_set_file_extent_num_bytes(leaf, fi,
args->start - key.offset);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
extent_offset += args->start - key.offset;
btrfs_set_file_extent_offset(leaf, fi, extent_offset);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - args->start);
btrfs_mark_buffer_dirty(trans, leaf);
if (update_refs && disk_bytenr > 0) {
struct btrfs_ref ref = {
.action = BTRFS_ADD_DELAYED_REF,
.bytenr = disk_bytenr,
.num_bytes = num_bytes,
.parent = 0,
.owning_root = btrfs_root_id(root),
.ref_root = btrfs_root_id(root),
};
btrfs_init_data_ref(&ref, new_key.objectid,
args->start - extent_offset,
0, false);
ret = btrfs_inc_extent_ref(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
}
key.offset = args->start;
}
/*
* From here on out we will have actually dropped something, so
* last_end can be updated.
*/
last_end = extent_end;
/*
* | ---- range to drop ----- |
* | -------- extent -------- |
*/
if (args->start <= key.offset && args->end < extent_end) {
if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
ret = -EOPNOTSUPP;
break;
}
memcpy(&new_key, &key, sizeof(new_key));
new_key.offset = args->end;
btrfs_set_item_key_safe(trans, path, &new_key);
extent_offset += args->end - key.offset;
btrfs_set_file_extent_offset(leaf, fi, extent_offset);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - args->end);
btrfs_mark_buffer_dirty(trans, leaf);
if (update_refs && disk_bytenr > 0)
args->bytes_found += args->end - key.offset;
break;
}
search_start = extent_end;
/*
* | ---- range to drop ----- |
* | -------- extent -------- |
*/
if (args->start > key.offset && args->end >= extent_end) {
BUG_ON(del_nr > 0);
if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
ret = -EOPNOTSUPP;
break;
}
btrfs_set_file_extent_num_bytes(leaf, fi,
args->start - key.offset);
btrfs_mark_buffer_dirty(trans, leaf);
if (update_refs && disk_bytenr > 0)
args->bytes_found += extent_end - args->start;
if (args->end == extent_end)
break;
path->slots[0]++;
goto next_slot;
}
/*
* | ---- range to drop ----- |
* | ------ extent ------ |
*/
if (args->start <= key.offset && args->end >= extent_end) {
delete_extent_item:
if (del_nr == 0) {
del_slot = path->slots[0];
del_nr = 1;
} else {
BUG_ON(del_slot + del_nr != path->slots[0]);
del_nr++;
}
if (update_refs &&
extent_type == BTRFS_FILE_EXTENT_INLINE) {
args->bytes_found += extent_end - key.offset;
extent_end = ALIGN(extent_end,
fs_info->sectorsize);
} else if (update_refs && disk_bytenr > 0) {
struct btrfs_ref ref = {
.action = BTRFS_DROP_DELAYED_REF,
.bytenr = disk_bytenr,
.num_bytes = num_bytes,
.parent = 0,
.owning_root = btrfs_root_id(root),
.ref_root = btrfs_root_id(root),
};
btrfs_init_data_ref(&ref, key.objectid,
key.offset - extent_offset,
0, false);
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
args->bytes_found += extent_end - key.offset;
}
if (args->end == extent_end)
break;
if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
path->slots[0]++;
goto next_slot;
}
ret = btrfs_del_items(trans, root, path, del_slot,
del_nr);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
del_nr = 0;
del_slot = 0;
btrfs_release_path(path);
continue;
}
BUG();
}
if (!ret && del_nr > 0) {
/*
* Set path->slots[0] to first slot, so that after the delete
* if items are move off from our leaf to its immediate left or
* right neighbor leafs, we end up with a correct and adjusted
* path->slots[0] for our insertion (if args->replace_extent).
*/
path->slots[0] = del_slot;
ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
if (ret)
btrfs_abort_transaction(trans, ret);
}
leaf = path->nodes[0];
/*
* If btrfs_del_items() was called, it might have deleted a leaf, in
* which case it unlocked our path, so check path->locks[0] matches a
* write lock.
*/
if (!ret && args->replace_extent &&
path->locks[0] == BTRFS_WRITE_LOCK &&
btrfs_leaf_free_space(leaf) >=
sizeof(struct btrfs_item) + args->extent_item_size) {
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = args->start;
if (!del_nr && path->slots[0] < btrfs_header_nritems(leaf)) {
struct btrfs_key slot_key;
btrfs_item_key_to_cpu(leaf, &slot_key, path->slots[0]);
if (btrfs_comp_cpu_keys(&key, &slot_key) > 0)
path->slots[0]++;
}
btrfs_setup_item_for_insert(trans, root, path, &key,
args->extent_item_size);
args->extent_inserted = true;
}
if (!args->path)
btrfs_free_path(path);
else if (!args->extent_inserted)
btrfs_release_path(path);
out:
args->drop_end = found ? min(args->end, last_end) : args->end;
return ret;
}
static int extent_mergeable(struct extent_buffer *leaf, int slot,
u64 objectid, u64 bytenr, u64 orig_offset,
u64 *start, u64 *end)
{
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
u64 extent_end;
if (slot < 0 || slot >= btrfs_header_nritems(leaf))
return 0;
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
return 0;
fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
btrfs_file_extent_compression(leaf, fi) ||
btrfs_file_extent_encryption(leaf, fi) ||
btrfs_file_extent_other_encoding(leaf, fi))
return 0;
extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
if ((*start && *start != key.offset) || (*end && *end != extent_end))
return 0;
*start = key.offset;
*end = extent_end;
return 1;
}
/*
* Mark extent in the range start - end as written.
*
* This changes extent type from 'pre-allocated' to 'regular'. If only
* part of extent is marked as written, the extent will be split into
* two or three.
*/
int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode, u64 start, u64 end)
{
struct btrfs_root *root = inode->root;
struct extent_buffer *leaf;
struct btrfs_path *path;
struct btrfs_file_extent_item *fi;
struct btrfs_ref ref = { 0 };
struct btrfs_key key;
struct btrfs_key new_key;
u64 bytenr;
u64 num_bytes;
u64 extent_end;
u64 orig_offset;
u64 other_start;
u64 other_end;
u64 split;
int del_nr = 0;
int del_slot = 0;
int recow;
int ret = 0;
u64 ino = btrfs_ino(inode);
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
again:
recow = 0;
split = start;
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = split;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto out;
if (ret > 0 && path->slots[0] > 0)
path->slots[0]--;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid != ino ||
key.type != BTRFS_EXTENT_DATA_KEY) {
ret = -EINVAL;
btrfs_abort_transaction(trans, ret);
goto out;
}
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_PREALLOC) {
ret = -EINVAL;
btrfs_abort_transaction(trans, ret);
goto out;
}
extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
if (key.offset > start || extent_end < end) {
ret = -EINVAL;
btrfs_abort_transaction(trans, ret);
goto out;
}
bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
memcpy(&new_key, &key, sizeof(new_key));
if (start == key.offset && end < extent_end) {
other_start = 0;
other_end = start;
if (extent_mergeable(leaf, path->slots[0] - 1,
ino, bytenr, orig_offset,
&other_start, &other_end)) {
new_key.offset = end;
btrfs_set_item_key_safe(trans, path, &new_key);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi,
trans->transid);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - end);
btrfs_set_file_extent_offset(leaf, fi,
end - orig_offset);
fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi,
trans->transid);
btrfs_set_file_extent_num_bytes(leaf, fi,
end - other_start);
btrfs_mark_buffer_dirty(trans, leaf);
goto out;
}
}
if (start > key.offset && end == extent_end) {
other_start = end;
other_end = 0;
if (extent_mergeable(leaf, path->slots[0] + 1,
ino, bytenr, orig_offset,
&other_start, &other_end)) {
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_num_bytes(leaf, fi,
start - key.offset);
btrfs_set_file_extent_generation(leaf, fi,
trans->transid);
path->slots[0]++;
new_key.offset = start;
btrfs_set_item_key_safe(trans, path, &new_key);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi,
trans->transid);
btrfs_set_file_extent_num_bytes(leaf, fi,
other_end - start);
btrfs_set_file_extent_offset(leaf, fi,
start - orig_offset);
btrfs_mark_buffer_dirty(trans, leaf);
goto out;
}
}
while (start > key.offset || end < extent_end) {
if (key.offset == start)
split = end;
new_key.offset = split;
ret = btrfs_duplicate_item(trans, root, path, &new_key);
if (ret == -EAGAIN) {
btrfs_release_path(path);
goto again;
}
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
leaf = path->nodes[0];
fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_set_file_extent_num_bytes(leaf, fi,
split - key.offset);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - split);
btrfs_mark_buffer_dirty(trans, leaf);
ref.action = BTRFS_ADD_DELAYED_REF;
ref.bytenr = bytenr;
ref.num_bytes = num_bytes;
ref.parent = 0;
ref.owning_root = btrfs_root_id(root);
ref.ref_root = btrfs_root_id(root);
btrfs_init_data_ref(&ref, ino, orig_offset, 0, false);
ret = btrfs_inc_extent_ref(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
if (split == start) {
key.offset = start;
} else {
if (start != key.offset) {
ret = -EINVAL;
btrfs_abort_transaction(trans, ret);
goto out;
}
path->slots[0]--;
extent_end = end;
}
recow = 1;
}
other_start = end;
other_end = 0;
ref.action = BTRFS_DROP_DELAYED_REF;
ref.bytenr = bytenr;
ref.num_bytes = num_bytes;
ref.parent = 0;
ref.owning_root = btrfs_root_id(root);
ref.ref_root = btrfs_root_id(root);
btrfs_init_data_ref(&ref, ino, orig_offset, 0, false);
if (extent_mergeable(leaf, path->slots[0] + 1,
ino, bytenr, orig_offset,
&other_start, &other_end)) {
if (recow) {
btrfs_release_path(path);
goto again;
}
extent_end = other_end;
del_slot = path->slots[0] + 1;
del_nr++;
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
}
other_start = 0;
other_end = start;
if (extent_mergeable(leaf, path->slots[0] - 1,
ino, bytenr, orig_offset,
&other_start, &other_end)) {
if (recow) {
btrfs_release_path(path);
goto again;
}
key.offset = other_start;
del_slot = path->slots[0];
del_nr++;
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
}
if (del_nr == 0) {
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
btrfs_set_file_extent_type(leaf, fi,
BTRFS_FILE_EXTENT_REG);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_mark_buffer_dirty(trans, leaf);
} else {
fi = btrfs_item_ptr(leaf, del_slot - 1,
struct btrfs_file_extent_item);
btrfs_set_file_extent_type(leaf, fi,
BTRFS_FILE_EXTENT_REG);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_set_file_extent_num_bytes(leaf, fi,
extent_end - key.offset);
btrfs_mark_buffer_dirty(trans, leaf);
ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
}
out:
btrfs_free_path(path);
return ret;
}
/*
* on error we return an unlocked page and the error value
* on success we return a locked page and 0
*/
static int prepare_uptodate_page(struct inode *inode,
struct page *page, u64 pos,
bool force_uptodate)
{
struct folio *folio = page_folio(page);
int ret = 0;
if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
!PageUptodate(page)) {
ret = btrfs_read_folio(NULL, folio);
if (ret)
return ret;
lock_page(page);
if (!PageUptodate(page)) {
unlock_page(page);
return -EIO;
}
/*
* Since btrfs_read_folio() will unlock the folio before it
* returns, there is a window where btrfs_release_folio() can be
* called to release the page. Here we check both inode
* mapping and PagePrivate() to make sure the page was not
* released.
*
* The private flag check is essential for subpage as we need
* to store extra bitmap using folio private.
*/
if (page->mapping != inode->i_mapping || !folio_test_private(folio)) {
unlock_page(page);
return -EAGAIN;
}
}
return 0;
}
static fgf_t get_prepare_fgp_flags(bool nowait)
{
fgf_t fgp_flags = FGP_LOCK | FGP_ACCESSED | FGP_CREAT;
if (nowait)
fgp_flags |= FGP_NOWAIT;
return fgp_flags;
}
static gfp_t get_prepare_gfp_flags(struct inode *inode, bool nowait)
{
gfp_t gfp;
gfp = btrfs_alloc_write_mask(inode->i_mapping);
if (nowait) {
gfp &= ~__GFP_DIRECT_RECLAIM;
gfp |= GFP_NOWAIT;
}
return gfp;
}
/*
* this just gets pages into the page cache and locks them down.
*/
static noinline int prepare_pages(struct inode *inode, struct page **pages,
size_t num_pages, loff_t pos,
size_t write_bytes, bool force_uptodate,
bool nowait)
{
int i;
unsigned long index = pos >> PAGE_SHIFT;
gfp_t mask = get_prepare_gfp_flags(inode, nowait);
fgf_t fgp_flags = get_prepare_fgp_flags(nowait);
int ret = 0;
int faili;
for (i = 0; i < num_pages; i++) {
again:
pages[i] = pagecache_get_page(inode->i_mapping, index + i,
fgp_flags, mask | __GFP_WRITE);
if (!pages[i]) {
faili = i - 1;
if (nowait)
ret = -EAGAIN;
else
ret = -ENOMEM;
goto fail;
}
ret = set_page_extent_mapped(pages[i]);
if (ret < 0) {
faili = i;
goto fail;
}
if (i == 0)
ret = prepare_uptodate_page(inode, pages[i], pos,
force_uptodate);
if (!ret && i == num_pages - 1)
ret = prepare_uptodate_page(inode, pages[i],
pos + write_bytes, false);
if (ret) {
put_page(pages[i]);
if (!nowait && ret == -EAGAIN) {
ret = 0;
goto again;
}
faili = i - 1;
goto fail;
}
wait_on_page_writeback(pages[i]);
}
return 0;
fail:
while (faili >= 0) {
unlock_page(pages[faili]);
put_page(pages[faili]);
faili--;
}
return ret;
}
/*
* This function locks the extent and properly waits for data=ordered extents
* to finish before allowing the pages to be modified if need.
*
* The return value:
* 1 - the extent is locked
* 0 - the extent is not locked, and everything is OK
* -EAGAIN - need re-prepare the pages
* the other < 0 number - Something wrong happens
*/
static noinline int
lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
size_t num_pages, loff_t pos,
size_t write_bytes,
u64 *lockstart, u64 *lockend, bool nowait,
struct extent_state **cached_state)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
u64 start_pos;
u64 last_pos;
int i;
int ret = 0;
start_pos = round_down(pos, fs_info->sectorsize);
last_pos = round_up(pos + write_bytes, fs_info->sectorsize) - 1;
if (start_pos < inode->vfs_inode.i_size) {
struct btrfs_ordered_extent *ordered;
if (nowait) {
if (!try_lock_extent(&inode->io_tree, start_pos, last_pos,
cached_state)) {
for (i = 0; i < num_pages; i++) {
unlock_page(pages[i]);
put_page(pages[i]);
pages[i] = NULL;
}
return -EAGAIN;
}
} else {
lock_extent(&inode->io_tree, start_pos, last_pos, cached_state);
}
ordered = btrfs_lookup_ordered_range(inode, start_pos,
last_pos - start_pos + 1);
if (ordered &&
ordered->file_offset + ordered->num_bytes > start_pos &&
ordered->file_offset <= last_pos) {
unlock_extent(&inode->io_tree, start_pos, last_pos,
cached_state);
for (i = 0; i < num_pages; i++) {
unlock_page(pages[i]);
put_page(pages[i]);
}
btrfs_start_ordered_extent(ordered);
btrfs_put_ordered_extent(ordered);
return -EAGAIN;
}
if (ordered)
btrfs_put_ordered_extent(ordered);
*lockstart = start_pos;
*lockend = last_pos;
ret = 1;
}
/*
* We should be called after prepare_pages() which should have locked
* all pages in the range.
*/
for (i = 0; i < num_pages; i++)
WARN_ON(!PageLocked(pages[i]));
return ret;
}
/*
* Check if we can do nocow write into the range [@pos, @pos + @write_bytes)
*
* @pos: File offset.
* @write_bytes: The length to write, will be updated to the nocow writeable
* range.
*
* This function will flush ordered extents in the range to ensure proper
* nocow checks.
*
* Return:
* > 0 If we can nocow, and updates @write_bytes.
* 0 If we can't do a nocow write.
* -EAGAIN If we can't do a nocow write because snapshoting of the inode's
* root is in progress.
* < 0 If an error happened.
*
* NOTE: Callers need to call btrfs_check_nocow_unlock() if we return > 0.
*/
int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
size_t *write_bytes, bool nowait)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct btrfs_root *root = inode->root;
struct extent_state *cached_state = NULL;
u64 lockstart, lockend;
u64 num_bytes;
int ret;
if (!(inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
return 0;
if (!btrfs_drew_try_write_lock(&root->snapshot_lock))
return -EAGAIN;
lockstart = round_down(pos, fs_info->sectorsize);
lockend = round_up(pos + *write_bytes,
fs_info->sectorsize) - 1;
num_bytes = lockend - lockstart + 1;
if (nowait) {
if (!btrfs_try_lock_ordered_range(inode, lockstart, lockend,
&cached_state)) {
btrfs_drew_write_unlock(&root->snapshot_lock);
return -EAGAIN;
}
} else {
btrfs_lock_and_flush_ordered_range(inode, lockstart, lockend,
&cached_state);
}
ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,
NULL, nowait, false);
if (ret <= 0)
btrfs_drew_write_unlock(&root->snapshot_lock);
else
*write_bytes = min_t(size_t, *write_bytes ,
num_bytes - pos + lockstart);
unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
return ret;
}
void btrfs_check_nocow_unlock(struct btrfs_inode *inode)
{
btrfs_drew_write_unlock(&inode->root->snapshot_lock);
}
static void update_time_for_write(struct inode *inode)
{
struct timespec64 now, ts;
if (IS_NOCMTIME(inode))
return;
now = current_time(inode);
ts = inode_get_mtime(inode);
if (!timespec64_equal(&ts, &now))
inode_set_mtime_to_ts(inode, now);
ts = inode_get_ctime(inode);
if (!timespec64_equal(&ts, &now))
inode_set_ctime_to_ts(inode, now);
if (IS_I_VERSION(inode))
inode_inc_iversion(inode);
}
int btrfs_write_check(struct kiocb *iocb, struct iov_iter *from, size_t count)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
loff_t pos = iocb->ki_pos;
int ret;
loff_t oldsize;
loff_t start_pos;
/*
* Quickly bail out on NOWAIT writes if we don't have the nodatacow or
* prealloc flags, as without those flags we always have to COW. We will
* later check if we can really COW into the target range (using
* can_nocow_extent() at btrfs_get_blocks_direct_write()).
*/
if ((iocb->ki_flags & IOCB_NOWAIT) &&
!(BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
return -EAGAIN;
ret = file_remove_privs(file);
if (ret)
return ret;
/*
* We reserve space for updating the inode when we reserve space for the
* extent we are going to write, so we will enospc out there. We don't
* need to start yet another transaction to update the inode as we will
* update the inode when we finish writing whatever data we write.
*/
update_time_for_write(inode);
start_pos = round_down(pos, fs_info->sectorsize);
oldsize = i_size_read(inode);
if (start_pos > oldsize) {
/* Expand hole size to cover write data, preventing empty gap */
loff_t end_pos = round_up(pos + count, fs_info->sectorsize);
ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, end_pos);
if (ret)
return ret;
}
return 0;
}
ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i)
{
struct file *file = iocb->ki_filp;
loff_t pos;
struct inode *inode = file_inode(file);
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct page **pages = NULL;
struct extent_changeset *data_reserved = NULL;
u64 release_bytes = 0;
u64 lockstart;
u64 lockend;
size_t num_written = 0;
int nrptrs;
ssize_t ret;
bool only_release_metadata = false;
bool force_page_uptodate = false;
loff_t old_isize = i_size_read(inode);
unsigned int ilock_flags = 0;
const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);
unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0);
if (nowait)
ilock_flags |= BTRFS_ILOCK_TRY;
ret = btrfs_inode_lock(BTRFS_I(inode), ilock_flags);
if (ret < 0)
return ret;
ret = generic_write_checks(iocb, i);
if (ret <= 0)
goto out;
ret = btrfs_write_check(iocb, i, ret);
if (ret < 0)
goto out;
pos = iocb->ki_pos;
nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
PAGE_SIZE / (sizeof(struct page *)));
nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
nrptrs = max(nrptrs, 8);
pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL);
if (!pages) {
ret = -ENOMEM;
goto out;
}
while (iov_iter_count(i) > 0) {
struct extent_state *cached_state = NULL;
size_t offset = offset_in_page(pos);
size_t sector_offset;
size_t write_bytes = min(iov_iter_count(i),
nrptrs * (size_t)PAGE_SIZE -
offset);
size_t num_pages;
size_t reserve_bytes;
size_t dirty_pages;
size_t copied;
size_t dirty_sectors;
size_t num_sectors;
int extents_locked;
/*
* Fault pages before locking them in prepare_pages
* to avoid recursive lock
*/
if (unlikely(fault_in_iov_iter_readable(i, write_bytes))) {
ret = -EFAULT;
break;
}
only_release_metadata = false;
sector_offset = pos & (fs_info->sectorsize - 1);
extent_changeset_release(data_reserved);
ret = btrfs_check_data_free_space(BTRFS_I(inode),
&data_reserved, pos,
write_bytes, nowait);
if (ret < 0) {
int can_nocow;
if (nowait && (ret == -ENOSPC || ret == -EAGAIN)) {
ret = -EAGAIN;
break;
}
/*
* If we don't have to COW at the offset, reserve
* metadata only. write_bytes may get smaller than
* requested here.
*/
can_nocow = btrfs_check_nocow_lock(BTRFS_I(inode), pos,
&write_bytes, nowait);
if (can_nocow < 0)
ret = can_nocow;
if (can_nocow > 0)
ret = 0;
if (ret)
break;
only_release_metadata = true;
}
num_pages = DIV_ROUND_UP(write_bytes + offset, PAGE_SIZE);
WARN_ON(num_pages > nrptrs);
reserve_bytes = round_up(write_bytes + sector_offset,
fs_info->sectorsize);
WARN_ON(reserve_bytes == 0);
ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
reserve_bytes,
reserve_bytes, nowait);
if (ret) {
if (!only_release_metadata)
btrfs_free_reserved_data_space(BTRFS_I(inode),
data_reserved, pos,
write_bytes);
else
btrfs_check_nocow_unlock(BTRFS_I(inode));
if (nowait && ret == -ENOSPC)
ret = -EAGAIN;
break;
}
release_bytes = reserve_bytes;
again:
ret = balance_dirty_pages_ratelimited_flags(inode->i_mapping, bdp_flags);
if (ret) {
btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);
break;
}
/*
* This is going to setup the pages array with the number of
* pages we want, so we don't really need to worry about the
* contents of pages from loop to loop
*/
ret = prepare_pages(inode, pages, num_pages,
pos, write_bytes, force_page_uptodate, false);
if (ret) {
btrfs_delalloc_release_extents(BTRFS_I(inode),
reserve_bytes);
break;
}
extents_locked = lock_and_cleanup_extent_if_need(
BTRFS_I(inode), pages,
num_pages, pos, write_bytes, &lockstart,
&lockend, nowait, &cached_state);
if (extents_locked < 0) {
if (!nowait && extents_locked == -EAGAIN)
goto again;
btrfs_delalloc_release_extents(BTRFS_I(inode),
reserve_bytes);
ret = extents_locked;
break;
}
copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes);
dirty_sectors = round_up(copied + sector_offset,
fs_info->sectorsize);
dirty_sectors = BTRFS_BYTES_TO_BLKS(fs_info, dirty_sectors);
/*
* if we have trouble faulting in the pages, fall
* back to one page at a time
*/
if (copied < write_bytes)
nrptrs = 1;
if (copied == 0) {
force_page_uptodate = true;
dirty_sectors = 0;
dirty_pages = 0;
} else {
force_page_uptodate = false;
dirty_pages = DIV_ROUND_UP(copied + offset,
PAGE_SIZE);
}
if (num_sectors > dirty_sectors) {
/* release everything except the sectors we dirtied */
release_bytes -= dirty_sectors << fs_info->sectorsize_bits;
if (only_release_metadata) {
btrfs_delalloc_release_metadata(BTRFS_I(inode),
release_bytes, true);
} else {
u64 __pos;
__pos = round_down(pos,
fs_info->sectorsize) +
(dirty_pages << PAGE_SHIFT);
btrfs_delalloc_release_space(BTRFS_I(inode),
data_reserved, __pos,
release_bytes, true);
}
}
release_bytes = round_up(copied + sector_offset,
fs_info->sectorsize);
ret = btrfs_dirty_pages(BTRFS_I(inode), pages,
dirty_pages, pos, copied,
&cached_state, only_release_metadata);
/*
* If we have not locked the extent range, because the range's
* start offset is >= i_size, we might still have a non-NULL
* cached extent state, acquired while marking the extent range
* as delalloc through btrfs_dirty_pages(). Therefore free any
* possible cached extent state to avoid a memory leak.
*/
if (extents_locked)
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart,
lockend, &cached_state);
else
free_extent_state(cached_state);
btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);
if (ret) {
btrfs_drop_pages(fs_info, pages, num_pages, pos, copied);
break;
}
release_bytes = 0;
if (only_release_metadata)
btrfs_check_nocow_unlock(BTRFS_I(inode));
btrfs_drop_pages(fs_info, pages, num_pages, pos, copied);
cond_resched();
pos += copied;
num_written += copied;
}
kfree(pages);
if (release_bytes) {
if (only_release_metadata) {
btrfs_check_nocow_unlock(BTRFS_I(inode));
btrfs_delalloc_release_metadata(BTRFS_I(inode),
release_bytes, true);
} else {
btrfs_delalloc_release_space(BTRFS_I(inode),
data_reserved,
round_down(pos, fs_info->sectorsize),
release_bytes, true);
}
}
extent_changeset_free(data_reserved);
if (num_written > 0) {
pagecache_isize_extended(inode, old_isize, iocb->ki_pos);
iocb->ki_pos += num_written;
}
out:
btrfs_inode_unlock(BTRFS_I(inode), ilock_flags);
return num_written ? num_written : ret;
}
static ssize_t btrfs_encoded_write(struct kiocb *iocb, struct iov_iter *from,
const struct btrfs_ioctl_encoded_io_args *encoded)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
loff_t count;
ssize_t ret;
btrfs_inode_lock(BTRFS_I(inode), 0);
count = encoded->len;
ret = generic_write_checks_count(iocb, &count);
if (ret == 0 && count != encoded->len) {
/*
* The write got truncated by generic_write_checks_count(). We
* can't do a partial encoded write.
*/
ret = -EFBIG;
}
if (ret || encoded->len == 0)
goto out;
ret = btrfs_write_check(iocb, from, encoded->len);
if (ret < 0)
goto out;
ret = btrfs_do_encoded_write(iocb, from, encoded);
out:
btrfs_inode_unlock(BTRFS_I(inode), 0);
return ret;
}
ssize_t btrfs_do_write_iter(struct kiocb *iocb, struct iov_iter *from,
const struct btrfs_ioctl_encoded_io_args *encoded)
{
struct file *file = iocb->ki_filp;
struct btrfs_inode *inode = BTRFS_I(file_inode(file));
ssize_t num_written, num_sync;
/*
* If the fs flips readonly due to some impossible error, although we
* have opened a file as writable, we have to stop this write operation
* to ensure consistency.
*/
if (BTRFS_FS_ERROR(inode->root->fs_info))
return -EROFS;
if (encoded && (iocb->ki_flags & IOCB_NOWAIT))
return -EOPNOTSUPP;
if (encoded) {
num_written = btrfs_encoded_write(iocb, from, encoded);
num_sync = encoded->len;
} else if (iocb->ki_flags & IOCB_DIRECT) {
num_written = btrfs_direct_write(iocb, from);
num_sync = num_written;
} else {
num_written = btrfs_buffered_write(iocb, from);
num_sync = num_written;
}
btrfs_set_inode_last_sub_trans(inode);
if (num_sync > 0) {
num_sync = generic_write_sync(iocb, num_sync);
if (num_sync < 0)
num_written = num_sync;
}
return num_written;
}
static ssize_t btrfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
return btrfs_do_write_iter(iocb, from, NULL);
}
int btrfs_release_file(struct inode *inode, struct file *filp)
{
struct btrfs_file_private *private = filp->private_data;
if (private) {
kfree(private->filldir_buf);
free_extent_state(private->llseek_cached_state);
kfree(private);
filp->private_data = NULL;
}
/*
* Set by setattr when we are about to truncate a file from a non-zero
* size to a zero size. This tries to flush down new bytes that may
* have been written if the application were using truncate to replace
* a file in place.
*/
if (test_and_clear_bit(BTRFS_INODE_FLUSH_ON_CLOSE,
&BTRFS_I(inode)->runtime_flags))
filemap_flush(inode->i_mapping);
return 0;
}
static int start_ordered_ops(struct btrfs_inode *inode, loff_t start, loff_t end)
{
int ret;
struct blk_plug plug;
/*
* This is only called in fsync, which would do synchronous writes, so
* a plug can merge adjacent IOs as much as possible. Esp. in case of
* multiple disks using raid profile, a large IO can be split to
* several segments of stripe length (currently 64K).
*/
blk_start_plug(&plug);
ret = btrfs_fdatawrite_range(inode, start, end);
blk_finish_plug(&plug);
return ret;
}
static inline bool skip_inode_logging(const struct btrfs_log_ctx *ctx)
{
struct btrfs_inode *inode = ctx->inode;
struct btrfs_fs_info *fs_info = inode->root->fs_info;
if (btrfs_inode_in_log(inode, btrfs_get_fs_generation(fs_info)) &&
list_empty(&ctx->ordered_extents))
return true;
/*
* If we are doing a fast fsync we can not bail out if the inode's
* last_trans is <= then the last committed transaction, because we only
* update the last_trans of the inode during ordered extent completion,
* and for a fast fsync we don't wait for that, we only wait for the
* writeback to complete.
*/
if (inode->last_trans <= btrfs_get_last_trans_committed(fs_info) &&
(test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags) ||
list_empty(&ctx->ordered_extents)))
return true;
return false;
}
/*
* fsync call for both files and directories. This logs the inode into
* the tree log instead of forcing full commits whenever possible.
*
* It needs to call filemap_fdatawait so that all ordered extent updates are
* in the metadata btree are up to date for copying to the log.
*
* It drops the inode mutex before doing the tree log commit. This is an
* important optimization for directories because holding the mutex prevents
* new operations on the dir while we write to disk.
*/
int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
struct dentry *dentry = file_dentry(file);
struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_trans_handle *trans;
struct btrfs_log_ctx ctx;
int ret = 0, err;
u64 len;
bool full_sync;
bool skip_ilock = false;
if (current->journal_info == BTRFS_TRANS_DIO_WRITE_STUB) {
skip_ilock = true;
current->journal_info = NULL;
btrfs_assert_inode_locked(inode);
}
trace_btrfs_sync_file(file, datasync);
btrfs_init_log_ctx(&ctx, inode);
/*
* Always set the range to a full range, otherwise we can get into
* several problems, from missing file extent items to represent holes
* when not using the NO_HOLES feature, to log tree corruption due to
* races between hole detection during logging and completion of ordered
* extents outside the range, to missing checksums due to ordered extents
* for which we flushed only a subset of their pages.
*/
start = 0;
end = LLONG_MAX;
len = (u64)LLONG_MAX + 1;
/*
* We write the dirty pages in the range and wait until they complete
* out of the ->i_mutex. If so, we can flush the dirty pages by
* multi-task, and make the performance up. See
* btrfs_wait_ordered_range for an explanation of the ASYNC check.
*/
ret = start_ordered_ops(inode, start, end);
if (ret)
goto out;
if (skip_ilock)
down_write(&inode->i_mmap_lock);
else
btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
atomic_inc(&root->log_batch);
/*
* Before we acquired the inode's lock and the mmap lock, someone may
* have dirtied more pages in the target range. We need to make sure
* that writeback for any such pages does not start while we are logging
* the inode, because if it does, any of the following might happen when
* we are not doing a full inode sync:
*
* 1) We log an extent after its writeback finishes but before its
* checksums are added to the csum tree, leading to -EIO errors
* when attempting to read the extent after a log replay.
*
* 2) We can end up logging an extent before its writeback finishes.
* Therefore after the log replay we will have a file extent item
* pointing to an unwritten extent (and no data checksums as well).
*
* So trigger writeback for any eventual new dirty pages and then we
* wait for all ordered extents to complete below.
*/
ret = start_ordered_ops(inode, start, end);
if (ret) {
if (skip_ilock)
up_write(&inode->i_mmap_lock);
else
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
goto out;
}
/*
* Always check for the full sync flag while holding the inode's lock,
* to avoid races with other tasks. The flag must be either set all the
* time during logging or always off all the time while logging.
* We check the flag here after starting delalloc above, because when
* running delalloc the full sync flag may be set if we need to drop
* extra extent map ranges due to temporary memory allocation failures.
*/
full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
/*
* We have to do this here to avoid the priority inversion of waiting on
* IO of a lower priority task while holding a transaction open.
*
* For a full fsync we wait for the ordered extents to complete while
* for a fast fsync we wait just for writeback to complete, and then
* attach the ordered extents to the transaction so that a transaction
* commit waits for their completion, to avoid data loss if we fsync,
* the current transaction commits before the ordered extents complete
* and a power failure happens right after that.
*
* For zoned filesystem, if a write IO uses a ZONE_APPEND command, the
* logical address recorded in the ordered extent may change. We need
* to wait for the IO to stabilize the logical address.
*/
if (full_sync || btrfs_is_zoned(fs_info)) {
ret = btrfs_wait_ordered_range(inode, start, len);
clear_bit(BTRFS_INODE_COW_WRITE_ERROR, &inode->runtime_flags);
} else {
/*
* Get our ordered extents as soon as possible to avoid doing
* checksum lookups in the csum tree, and use instead the
* checksums attached to the ordered extents.
*/
btrfs_get_ordered_extents_for_logging(inode, &ctx.ordered_extents);
ret = filemap_fdatawait_range(inode->vfs_inode.i_mapping, start, end);
if (ret)
goto out_release_extents;
/*
* Check and clear the BTRFS_INODE_COW_WRITE_ERROR now after
* starting and waiting for writeback, because for buffered IO
* it may have been set during the end IO callback
* (end_bbio_data_write() -> btrfs_finish_ordered_extent()) in
* case an error happened and we need to wait for ordered
* extents to complete so that any extent maps that point to
* unwritten locations are dropped and we don't log them.
*/
if (test_and_clear_bit(BTRFS_INODE_COW_WRITE_ERROR, &inode->runtime_flags))
ret = btrfs_wait_ordered_range(inode, start, len);
}
if (ret)
goto out_release_extents;
atomic_inc(&root->log_batch);
if (skip_inode_logging(&ctx)) {
/*
* We've had everything committed since the last time we were
* modified so clear this flag in case it was set for whatever
* reason, it's no longer relevant.
*/
clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
/*
* An ordered extent might have started before and completed
* already with io errors, in which case the inode was not
* updated and we end up here. So check the inode's mapping
* for any errors that might have happened since we last
* checked called fsync.
*/
ret = filemap_check_wb_err(inode->vfs_inode.i_mapping, file->f_wb_err);
goto out_release_extents;
}
btrfs_init_log_ctx_scratch_eb(&ctx);
/*
* We use start here because we will need to wait on the IO to complete
* in btrfs_sync_log, which could require joining a transaction (for
* example checking cross references in the nocow path). If we use join
* here we could get into a situation where we're waiting on IO to
* happen that is blocked on a transaction trying to commit. With start
* we inc the extwriter counter, so we wait for all extwriters to exit
* before we start blocking joiners. This comment is to keep somebody
* from thinking they are super smart and changing this to
* btrfs_join_transaction *cough*Josef*cough*.
*/
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out_release_extents;
}
trans->in_fsync = true;
ret = btrfs_log_dentry_safe(trans, dentry, &ctx);
/*
* Scratch eb no longer needed, release before syncing log or commit
* transaction, to avoid holding unnecessary memory during such long
* operations.
*/
if (ctx.scratch_eb) {
free_extent_buffer(ctx.scratch_eb);
ctx.scratch_eb = NULL;
}
btrfs_release_log_ctx_extents(&ctx);
if (ret < 0) {
/* Fallthrough and commit/free transaction. */
ret = BTRFS_LOG_FORCE_COMMIT;
}
/* we've logged all the items and now have a consistent
* version of the file in the log. It is possible that
* someone will come in and modify the file, but that's
* fine because the log is consistent on disk, and we
* have references to all of the file's extents
*
* It is possible that someone will come in and log the
* file again, but that will end up using the synchronization
* inside btrfs_sync_log to keep things safe.
*/
if (skip_ilock)
up_write(&inode->i_mmap_lock);
else
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
if (ret == BTRFS_NO_LOG_SYNC) {
ret = btrfs_end_transaction(trans);
goto out;
}
/* We successfully logged the inode, attempt to sync the log. */
if (!ret) {
ret = btrfs_sync_log(trans, root, &ctx);
if (!ret) {
ret = btrfs_end_transaction(trans);
goto out;
}
}
/*
* At this point we need to commit the transaction because we had
* btrfs_need_log_full_commit() or some other error.
*
* If we didn't do a full sync we have to stop the trans handle, wait on
* the ordered extents, start it again and commit the transaction. If
* we attempt to wait on the ordered extents here we could deadlock with
* something like fallocate() that is holding the extent lock trying to
* start a transaction while some other thread is trying to commit the
* transaction while we (fsync) are currently holding the transaction
* open.
*/
if (!full_sync) {
ret = btrfs_end_transaction(trans);
if (ret)
goto out;
ret = btrfs_wait_ordered_range(inode, start, len);
if (ret)
goto out;
/*
* This is safe to use here because we're only interested in
* making sure the transaction that had the ordered extents is
* committed. We aren't waiting on anything past this point,
* we're purely getting the transaction and committing it.
*/
trans = btrfs_attach_transaction_barrier(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
/*
* We committed the transaction and there's no currently
* running transaction, this means everything we care
* about made it to disk and we are done.
*/
if (ret == -ENOENT)
ret = 0;
goto out;
}
}
ret = btrfs_commit_transaction(trans);
out:
free_extent_buffer(ctx.scratch_eb);
ASSERT(list_empty(&ctx.list));
ASSERT(list_empty(&ctx.conflict_inodes));
err = file_check_and_advance_wb_err(file);
if (!ret)
ret = err;
return ret > 0 ? -EIO : ret;
out_release_extents:
btrfs_release_log_ctx_extents(&ctx);
if (skip_ilock)
up_write(&inode->i_mmap_lock);
else
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
goto out;
}
/*
* btrfs_page_mkwrite() is not allowed to change the file size as it gets
* called from a page fault handler when a page is first dirtied. Hence we must
* be careful to check for EOF conditions here. We set the page up correctly
* for a written page which means we get ENOSPC checking when writing into
* holes and correct delalloc and unwritten extent mapping on filesystems that
* support these features.
*
* We are not allowed to take the i_mutex here so we have to play games to
* protect against truncate races as the page could now be beyond EOF. Because
* truncate_setsize() writes the inode size before removing pages, once we have
* the page lock we can determine safely if the page is beyond EOF. If it is not
* beyond EOF, then the page is guaranteed safe against truncation until we
* unlock the page.
*/
static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
{
struct page *page = vmf->page;
struct folio *folio = page_folio(page);
struct inode *inode = file_inode(vmf->vma->vm_file);
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct btrfs_ordered_extent *ordered;
struct extent_state *cached_state = NULL;
struct extent_changeset *data_reserved = NULL;
unsigned long zero_start;
loff_t size;
vm_fault_t ret;
int ret2;
int reserved = 0;
u64 reserved_space;
u64 page_start;
u64 page_end;
u64 end;
ASSERT(folio_order(folio) == 0);
reserved_space = PAGE_SIZE;
sb_start_pagefault(inode->i_sb);
page_start = folio_pos(folio);
page_end = page_start + folio_size(folio) - 1;
end = page_end;
/*
* Reserving delalloc space after obtaining the page lock can lead to
* deadlock. For example, if a dirty page is locked by this function
* and the call to btrfs_delalloc_reserve_space() ends up triggering
* dirty page write out, then the btrfs_writepages() function could
* end up waiting indefinitely to get a lock on the page currently
* being processed by btrfs_page_mkwrite() function.
*/
ret2 = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
page_start, reserved_space);
if (!ret2) {
ret2 = file_update_time(vmf->vma->vm_file);
reserved = 1;
}
if (ret2) {
ret = vmf_error(ret2);
if (reserved)
goto out;
goto out_noreserve;
}
/* Make the VM retry the fault. */
ret = VM_FAULT_NOPAGE;
again:
down_read(&BTRFS_I(inode)->i_mmap_lock);
folio_lock(folio);
size = i_size_read(inode);
if ((folio->mapping != inode->i_mapping) ||
(page_start >= size)) {
/* Page got truncated out from underneath us. */
goto out_unlock;
}
folio_wait_writeback(folio);
lock_extent(io_tree, page_start, page_end, &cached_state);
ret2 = set_folio_extent_mapped(folio);
if (ret2 < 0) {
ret = vmf_error(ret2);
unlock_extent(io_tree, page_start, page_end, &cached_state);
goto out_unlock;
}
/*
* We can't set the delalloc bits if there are pending ordered
* extents. Drop our locks and wait for them to finish.
*/
ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, PAGE_SIZE);
if (ordered) {
unlock_extent(io_tree, page_start, page_end, &cached_state);
folio_unlock(folio);
up_read(&BTRFS_I(inode)->i_mmap_lock);
btrfs_start_ordered_extent(ordered);
btrfs_put_ordered_extent(ordered);
goto again;
}
if (folio->index == ((size - 1) >> PAGE_SHIFT)) {
reserved_space = round_up(size - page_start, fs_info->sectorsize);
if (reserved_space < PAGE_SIZE) {
end = page_start + reserved_space - 1;
btrfs_delalloc_release_space(BTRFS_I(inode),
data_reserved, page_start,
PAGE_SIZE - reserved_space, true);
}
}
/*
* page_mkwrite gets called when the page is firstly dirtied after it's
* faulted in, but write(2) could also dirty a page and set delalloc
* bits, thus in this case for space account reason, we still need to
* clear any delalloc bits within this page range since we have to
* reserve data&meta space before lock_page() (see above comments).
*/
clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end,
EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
EXTENT_DEFRAG, &cached_state);
ret2 = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, end, 0,
&cached_state);
if (ret2) {
unlock_extent(io_tree, page_start, page_end, &cached_state);
ret = VM_FAULT_SIGBUS;
goto out_unlock;
}
/* Page is wholly or partially inside EOF. */
if (page_start + folio_size(folio) > size)
zero_start = offset_in_folio(folio, size);
else
zero_start = PAGE_SIZE;
if (zero_start != PAGE_SIZE)
folio_zero_range(folio, zero_start, folio_size(folio) - zero_start);
btrfs_folio_clear_checked(fs_info, folio, page_start, PAGE_SIZE);
btrfs_folio_set_dirty(fs_info, folio, page_start, end + 1 - page_start);
btrfs_folio_set_uptodate(fs_info, folio, page_start, end + 1 - page_start);
btrfs_set_inode_last_sub_trans(BTRFS_I(inode));
unlock_extent(io_tree, page_start, page_end, &cached_state);
up_read(&BTRFS_I(inode)->i_mmap_lock);
btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
sb_end_pagefault(inode->i_sb);
extent_changeset_free(data_reserved);
return VM_FAULT_LOCKED;
out_unlock:
folio_unlock(folio);
up_read(&BTRFS_I(inode)->i_mmap_lock);
out:
btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start,
reserved_space, (ret != 0));
out_noreserve:
sb_end_pagefault(inode->i_sb);
extent_changeset_free(data_reserved);
return ret;
}
static const struct vm_operations_struct btrfs_file_vm_ops = {
.fault = filemap_fault,
.map_pages = filemap_map_pages,
.page_mkwrite = btrfs_page_mkwrite,
};
static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
{
struct address_space *mapping = filp->f_mapping;
if (!mapping->a_ops->read_folio)
return -ENOEXEC;
file_accessed(filp);
vma->vm_ops = &btrfs_file_vm_ops;
return 0;
}
static int hole_mergeable(struct btrfs_inode *inode, struct extent_buffer *leaf,
int slot, u64 start, u64 end)
{
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
if (slot < 0 || slot >= btrfs_header_nritems(leaf))
return 0;
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != btrfs_ino(inode) ||
key.type != BTRFS_EXTENT_DATA_KEY)
return 0;
fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
return 0;
if (btrfs_file_extent_disk_bytenr(leaf, fi))
return 0;
if (key.offset == end)
return 1;
if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
return 1;
return 0;
}
static int fill_holes(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode,
struct btrfs_path *path, u64 offset, u64 end)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root = inode->root;
struct extent_buffer *leaf;
struct btrfs_file_extent_item *fi;
struct extent_map *hole_em;
struct btrfs_key key;
int ret;
if (btrfs_fs_incompat(fs_info, NO_HOLES))
goto out;
key.objectid = btrfs_ino(inode);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = offset;
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (ret <= 0) {
/*
* We should have dropped this offset, so if we find it then
* something has gone horribly wrong.
*/
if (ret == 0)
ret = -EINVAL;
return ret;
}
leaf = path->nodes[0];
if (hole_mergeable(inode, leaf, path->slots[0] - 1, offset, end)) {
u64 num_bytes;
path->slots[0]--;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
end - offset;
btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_offset(leaf, fi, 0);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_mark_buffer_dirty(trans, leaf);
goto out;
}
if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
u64 num_bytes;
key.offset = offset;
btrfs_set_item_key_safe(trans, path, &key);
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
offset;
btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
btrfs_set_file_extent_offset(leaf, fi, 0);
btrfs_set_file_extent_generation(leaf, fi, trans->transid);
btrfs_mark_buffer_dirty(trans, leaf);
goto out;
}
btrfs_release_path(path);
ret = btrfs_insert_hole_extent(trans, root, btrfs_ino(inode), offset,
end - offset);
if (ret)
return ret;
out:
btrfs_release_path(path);
hole_em = alloc_extent_map();
if (!hole_em) {
btrfs_drop_extent_map_range(inode, offset, end - 1, false);
btrfs_set_inode_full_sync(inode);
} else {
hole_em->start = offset;
hole_em->len = end - offset;
hole_em->ram_bytes = hole_em->len;
hole_em->disk_bytenr = EXTENT_MAP_HOLE;
hole_em->disk_num_bytes = 0;
hole_em->generation = trans->transid;
ret = btrfs_replace_extent_map_range(inode, hole_em, true);
free_extent_map(hole_em);
if (ret)
btrfs_set_inode_full_sync(inode);
}
return 0;
}
/*
* Find a hole extent on given inode and change start/len to the end of hole
* extent.(hole/vacuum extent whose em->start <= start &&
* em->start + em->len > start)
* When a hole extent is found, return 1 and modify start/len.
*/
static int find_first_non_hole(struct btrfs_inode *inode, u64 *start, u64 *len)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct extent_map *em;
int ret = 0;
em = btrfs_get_extent(inode, NULL,
round_down(*start, fs_info->sectorsize),
round_up(*len, fs_info->sectorsize));
if (IS_ERR(em))
return PTR_ERR(em);
/* Hole or vacuum extent(only exists in no-hole mode) */
if (em->disk_bytenr == EXTENT_MAP_HOLE) {
ret = 1;
*len = em->start + em->len > *start + *len ?
0 : *start + *len - em->start - em->len;
*start = em->start + em->len;
}
free_extent_map(em);
return ret;
}
static void btrfs_punch_hole_lock_range(struct inode *inode,
const u64 lockstart,
const u64 lockend,
struct extent_state **cached_state)
{
/*
* For subpage case, if the range is not at page boundary, we could
* have pages at the leading/tailing part of the range.
* This could lead to dead loop since filemap_range_has_page()
* will always return true.
* So here we need to do extra page alignment for
* filemap_range_has_page().
*/
const u64 page_lockstart = round_up(lockstart, PAGE_SIZE);
const u64 page_lockend = round_down(lockend + 1, PAGE_SIZE) - 1;
while (1) {
truncate_pagecache_range(inode, lockstart, lockend);
lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
cached_state);
/*
* We can't have ordered extents in the range, nor dirty/writeback
* pages, because we have locked the inode's VFS lock in exclusive
* mode, we have locked the inode's i_mmap_lock in exclusive mode,
* we have flushed all delalloc in the range and we have waited
* for any ordered extents in the range to complete.
* We can race with anyone reading pages from this range, so after
* locking the range check if we have pages in the range, and if
* we do, unlock the range and retry.
*/
if (!filemap_range_has_page(inode->i_mapping, page_lockstart,
page_lockend))
break;
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
cached_state);
}
btrfs_assert_inode_range_clean(BTRFS_I(inode), lockstart, lockend);
}
static int btrfs_insert_replace_extent(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode,
struct btrfs_path *path,
struct btrfs_replace_extent_info *extent_info,
const u64 replace_len,
const u64 bytes_to_drop)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root = inode->root;
struct btrfs_file_extent_item *extent;
struct extent_buffer *leaf;
struct btrfs_key key;
int slot;
int ret;
if (replace_len == 0)
return 0;
if (extent_info->disk_offset == 0 &&
btrfs_fs_incompat(fs_info, NO_HOLES)) {
btrfs_update_inode_bytes(inode, 0, bytes_to_drop);
return 0;
}
key.objectid = btrfs_ino(inode);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = extent_info->file_offset;
ret = btrfs_insert_empty_item(trans, root, path, &key,
sizeof(struct btrfs_file_extent_item));
if (ret)
return ret;
leaf = path->nodes[0];
slot = path->slots[0];
write_extent_buffer(leaf, extent_info->extent_buf,
btrfs_item_ptr_offset(leaf, slot),
sizeof(struct btrfs_file_extent_item));
extent = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
ASSERT(btrfs_file_extent_type(leaf, extent) != BTRFS_FILE_EXTENT_INLINE);
btrfs_set_file_extent_offset(leaf, extent, extent_info->data_offset);
btrfs_set_file_extent_num_bytes(leaf, extent, replace_len);
if (extent_info->is_new_extent)
btrfs_set_file_extent_generation(leaf, extent, trans->transid);
btrfs_mark_buffer_dirty(trans, leaf);
btrfs_release_path(path);
ret = btrfs_inode_set_file_extent_range(inode, extent_info->file_offset,
replace_len);
if (ret)
return ret;
/* If it's a hole, nothing more needs to be done. */
if (extent_info->disk_offset == 0) {
btrfs_update_inode_bytes(inode, 0, bytes_to_drop);
return 0;
}
btrfs_update_inode_bytes(inode, replace_len, bytes_to_drop);
if (extent_info->is_new_extent && extent_info->insertions == 0) {
key.objectid = extent_info->disk_offset;
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = extent_info->disk_len;
ret = btrfs_alloc_reserved_file_extent(trans, root,
btrfs_ino(inode),
extent_info->file_offset,
extent_info->qgroup_reserved,
&key);
} else {
struct btrfs_ref ref = {
.action = BTRFS_ADD_DELAYED_REF,
.bytenr = extent_info->disk_offset,
.num_bytes = extent_info->disk_len,
.owning_root = btrfs_root_id(root),
.ref_root = btrfs_root_id(root),
};
u64 ref_offset;
ref_offset = extent_info->file_offset - extent_info->data_offset;
btrfs_init_data_ref(&ref, btrfs_ino(inode), ref_offset, 0, false);
ret = btrfs_inc_extent_ref(trans, &ref);
}
extent_info->insertions++;
return ret;
}
/*
* The respective range must have been previously locked, as well as the inode.
* The end offset is inclusive (last byte of the range).
* @extent_info is NULL for fallocate's hole punching and non-NULL when replacing
* the file range with an extent.
* When not punching a hole, we don't want to end up in a state where we dropped
* extents without inserting a new one, so we must abort the transaction to avoid
* a corruption.
*/
int btrfs_replace_file_extents(struct btrfs_inode *inode,
struct btrfs_path *path, const u64 start,
const u64 end,
struct btrfs_replace_extent_info *extent_info,
struct btrfs_trans_handle **trans_out)
{
struct btrfs_drop_extents_args drop_args = { 0 };
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
u64 min_size = btrfs_calc_insert_metadata_size(fs_info, 1);
u64 ino_size = round_up(inode->vfs_inode.i_size, fs_info->sectorsize);
struct btrfs_trans_handle *trans = NULL;
struct btrfs_block_rsv *rsv;
unsigned int rsv_count;
u64 cur_offset;
u64 len = end - start;
int ret = 0;
if (end <= start)
return -EINVAL;
rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
if (!rsv) {
ret = -ENOMEM;
goto out;
}
rsv->size = btrfs_calc_insert_metadata_size(fs_info, 1);
rsv->failfast = true;
/*
* 1 - update the inode
* 1 - removing the extents in the range
* 1 - adding the hole extent if no_holes isn't set or if we are
* replacing the range with a new extent
*/
if (!btrfs_fs_incompat(fs_info, NO_HOLES) || extent_info)
rsv_count = 3;
else
rsv_count = 2;
trans = btrfs_start_transaction(root, rsv_count);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
trans = NULL;
goto out_free;
}
ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
min_size, false);
if (WARN_ON(ret))
goto out_trans;
trans->block_rsv = rsv;
cur_offset = start;
drop_args.path = path;
drop_args.end = end + 1;
drop_args.drop_cache = true;
while (cur_offset < end) {
drop_args.start = cur_offset;
ret = btrfs_drop_extents(trans, root, inode, &drop_args);
/* If we are punching a hole decrement the inode's byte count */
if (!extent_info)
btrfs_update_inode_bytes(inode, 0,
drop_args.bytes_found);
if (ret != -ENOSPC) {
/*
* The only time we don't want to abort is if we are
* attempting to clone a partial inline extent, in which
* case we'll get EOPNOTSUPP. However if we aren't
* clone we need to abort no matter what, because if we
* got EOPNOTSUPP via prealloc then we messed up and
* need to abort.
*/
if (ret &&
(ret != -EOPNOTSUPP ||
(extent_info && extent_info->is_new_extent)))
btrfs_abort_transaction(trans, ret);
break;
}
trans->block_rsv = &fs_info->trans_block_rsv;
if (!extent_info && cur_offset < drop_args.drop_end &&
cur_offset < ino_size) {
ret = fill_holes(trans, inode, path, cur_offset,
drop_args.drop_end);
if (ret) {
/*
* If we failed then we didn't insert our hole
* entries for the area we dropped, so now the
* fs is corrupted, so we must abort the
* transaction.
*/
btrfs_abort_transaction(trans, ret);
break;
}
} else if (!extent_info && cur_offset < drop_args.drop_end) {
/*
* We are past the i_size here, but since we didn't
* insert holes we need to clear the mapped area so we
* know to not set disk_i_size in this area until a new
* file extent is inserted here.
*/
ret = btrfs_inode_clear_file_extent_range(inode,
cur_offset,
drop_args.drop_end - cur_offset);
if (ret) {
/*
* We couldn't clear our area, so we could
* presumably adjust up and corrupt the fs, so
* we need to abort.
*/
btrfs_abort_transaction(trans, ret);
break;
}
}
if (extent_info &&
drop_args.drop_end > extent_info->file_offset) {
u64 replace_len = drop_args.drop_end -
extent_info->file_offset;
ret = btrfs_insert_replace_extent(trans, inode, path,
extent_info, replace_len,
drop_args.bytes_found);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
extent_info->data_len -= replace_len;
extent_info->data_offset += replace_len;
extent_info->file_offset += replace_len;
}
/*
* We are releasing our handle on the transaction, balance the
* dirty pages of the btree inode and flush delayed items, and
* then get a new transaction handle, which may now point to a
* new transaction in case someone else may have committed the
* transaction we used to replace/drop file extent items. So
* bump the inode's iversion and update mtime and ctime except
* if we are called from a dedupe context. This is because a
* power failure/crash may happen after the transaction is
* committed and before we finish replacing/dropping all the
* file extent items we need.
*/
inode_inc_iversion(&inode->vfs_inode);
if (!extent_info || extent_info->update_times)
inode_set_mtime_to_ts(&inode->vfs_inode,
inode_set_ctime_current(&inode->vfs_inode));
ret = btrfs_update_inode(trans, inode);
if (ret)
break;
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
trans = btrfs_start_transaction(root, rsv_count);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
trans = NULL;
break;
}
ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
rsv, min_size, false);
if (WARN_ON(ret))
break;
trans->block_rsv = rsv;
cur_offset = drop_args.drop_end;
len = end - cur_offset;
if (!extent_info && len) {
ret = find_first_non_hole(inode, &cur_offset, &len);
if (unlikely(ret < 0))
break;
if (ret && !len) {
ret = 0;
break;
}
}
}
/*
* If we were cloning, force the next fsync to be a full one since we
* we replaced (or just dropped in the case of cloning holes when
* NO_HOLES is enabled) file extent items and did not setup new extent
* maps for the replacement extents (or holes).
*/
if (extent_info && !extent_info->is_new_extent)
btrfs_set_inode_full_sync(inode);
if (ret)
goto out_trans;
trans->block_rsv = &fs_info->trans_block_rsv;
/*
* If we are using the NO_HOLES feature we might have had already an
* hole that overlaps a part of the region [lockstart, lockend] and
* ends at (or beyond) lockend. Since we have no file extent items to
* represent holes, drop_end can be less than lockend and so we must
* make sure we have an extent map representing the existing hole (the
* call to __btrfs_drop_extents() might have dropped the existing extent
* map representing the existing hole), otherwise the fast fsync path
* will not record the existence of the hole region
* [existing_hole_start, lockend].
*/
if (drop_args.drop_end <= end)
drop_args.drop_end = end + 1;
/*
* Don't insert file hole extent item if it's for a range beyond eof
* (because it's useless) or if it represents a 0 bytes range (when
* cur_offset == drop_end).
*/
if (!extent_info && cur_offset < ino_size &&
cur_offset < drop_args.drop_end) {
ret = fill_holes(trans, inode, path, cur_offset,
drop_args.drop_end);
if (ret) {
/* Same comment as above. */
btrfs_abort_transaction(trans, ret);
goto out_trans;
}
} else if (!extent_info && cur_offset < drop_args.drop_end) {
/* See the comment in the loop above for the reasoning here. */
ret = btrfs_inode_clear_file_extent_range(inode, cur_offset,
drop_args.drop_end - cur_offset);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out_trans;
}
}
if (extent_info) {
ret = btrfs_insert_replace_extent(trans, inode, path,
extent_info, extent_info->data_len,
drop_args.bytes_found);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out_trans;
}
}
out_trans:
if (!trans)
goto out_free;
trans->block_rsv = &fs_info->trans_block_rsv;
if (ret)
btrfs_end_transaction(trans);
else
*trans_out = trans;
out_free:
btrfs_free_block_rsv(fs_info, rsv);
out:
return ret;
}
static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len)
{
struct inode *inode = file_inode(file);
struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
struct btrfs_root *root = BTRFS_I(inode)->root;
struct extent_state *cached_state = NULL;
struct btrfs_path *path;
struct btrfs_trans_handle *trans = NULL;
u64 lockstart;
u64 lockend;
u64 tail_start;
u64 tail_len;
u64 orig_start = offset;
int ret = 0;
bool same_block;
u64 ino_size;
bool truncated_block = false;
bool updated_inode = false;
btrfs_inode_lock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
ret = btrfs_wait_ordered_range(BTRFS_I(inode), offset, len);
if (ret)
goto out_only_mutex;
ino_size = round_up(inode->i_size, fs_info->sectorsize);
ret = find_first_non_hole(BTRFS_I(inode), &offset, &len);
if (ret < 0)
goto out_only_mutex;
if (ret && !len) {
/* Already in a large hole */
ret = 0;
goto out_only_mutex;
}
ret = file_modified(file);
if (ret)
goto out_only_mutex;
lockstart = round_up(offset, fs_info->sectorsize);
lockend = round_down(offset + len, fs_info->sectorsize) - 1;
same_block = (BTRFS_BYTES_TO_BLKS(fs_info, offset))
== (BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1));
/*
* We needn't truncate any block which is beyond the end of the file
* because we are sure there is no data there.
*/
/*
* Only do this if we are in the same block and we aren't doing the
* entire block.
*/
if (same_block && len < fs_info->sectorsize) {
if (offset < ino_size) {
truncated_block = true;
ret = btrfs_truncate_block(BTRFS_I(inode), offset, len,
0);
} else {
ret = 0;
}
goto out_only_mutex;
}
/* zero back part of the first block */
if (offset < ino_size) {
truncated_block = true;
ret = btrfs_truncate_block(BTRFS_I(inode), offset, 0, 0);
if (ret) {
btrfs_inode_unlock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
return ret;
}
}
/* Check the aligned pages after the first unaligned page,
* if offset != orig_start, which means the first unaligned page
* including several following pages are already in holes,
* the extra check can be skipped */
if (offset == orig_start) {
/* after truncate page, check hole again */
len = offset + len - lockstart;
offset = lockstart;
ret = find_first_non_hole(BTRFS_I(inode), &offset, &len);
if (ret < 0)
goto out_only_mutex;
if (ret && !len) {
ret = 0;
goto out_only_mutex;
}
lockstart = offset;
}
/* Check the tail unaligned part is in a hole */
tail_start = lockend + 1;
tail_len = offset + len - tail_start;
if (tail_len) {
ret = find_first_non_hole(BTRFS_I(inode), &tail_start, &tail_len);
if (unlikely(ret < 0))
goto out_only_mutex;
if (!ret) {
/* zero the front end of the last page */
if (tail_start + tail_len < ino_size) {
truncated_block = true;
ret = btrfs_truncate_block(BTRFS_I(inode),
tail_start + tail_len,
0, 1);
if (ret)
goto out_only_mutex;
}
}
}
if (lockend < lockstart) {
ret = 0;
goto out_only_mutex;
}
btrfs_punch_hole_lock_range(inode, lockstart, lockend, &cached_state);
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
ret = btrfs_replace_file_extents(BTRFS_I(inode), path, lockstart,
lockend, NULL, &trans);
btrfs_free_path(path);
if (ret)
goto out;
ASSERT(trans != NULL);
inode_inc_iversion(inode);
inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
ret = btrfs_update_inode(trans, BTRFS_I(inode));
updated_inode = true;
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
out:
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
&cached_state);
out_only_mutex:
if (!updated_inode && truncated_block && !ret) {
/*
* If we only end up zeroing part of a page, we still need to
* update the inode item, so that all the time fields are
* updated as well as the necessary btrfs inode in memory fields
* for detecting, at fsync time, if the inode isn't yet in the
* log tree or it's there but not up to date.
*/
struct timespec64 now = inode_set_ctime_current(inode);
inode_inc_iversion(inode);
inode_set_mtime_to_ts(inode, now);
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
} else {
int ret2;
ret = btrfs_update_inode(trans, BTRFS_I(inode));
ret2 = btrfs_end_transaction(trans);
if (!ret)
ret = ret2;
}
}
btrfs_inode_unlock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
return ret;
}
/* Helper structure to record which range is already reserved */
struct falloc_range {
struct list_head list;
u64 start;
u64 len;
};
/*
* Helper function to add falloc range
*
* Caller should have locked the larger range of extent containing
* [start, len)
*/
static int add_falloc_range(struct list_head *head, u64 start, u64 len)
{
struct falloc_range *range = NULL;
if (!list_empty(head)) {
/*
* As fallocate iterates by bytenr order, we only need to check
* the last range.
*/
range = list_last_entry(head, struct falloc_range, list);
if (range->start + range->len == start) {
range->len += len;
return 0;
}
}
range = kmalloc(sizeof(*range), GFP_KERNEL);
if (!range)
return -ENOMEM;
range->start = start;
range->len = len;
list_add_tail(&range->list, head);
return 0;
}
static int btrfs_fallocate_update_isize(struct inode *inode,
const u64 end,
const int mode)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *root = BTRFS_I(inode)->root;
int ret;
int ret2;
if (mode & FALLOC_FL_KEEP_SIZE || end <= i_size_read(inode))
return 0;
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans))
return PTR_ERR(trans);
inode_set_ctime_current(inode);
i_size_write(inode, end);
btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
ret = btrfs_update_inode(trans, BTRFS_I(inode));
ret2 = btrfs_end_transaction(trans);
return ret ? ret : ret2;
}
enum {
RANGE_BOUNDARY_WRITTEN_EXTENT,
RANGE_BOUNDARY_PREALLOC_EXTENT,
RANGE_BOUNDARY_HOLE,
};
static int btrfs_zero_range_check_range_boundary(struct btrfs_inode *inode,
u64 offset)
{
const u64 sectorsize = inode->root->fs_info->sectorsize;
struct extent_map *em;
int ret;
offset = round_down(offset, sectorsize);
em = btrfs_get_extent(inode, NULL, offset, sectorsize);
if (IS_ERR(em))
return PTR_ERR(em);
if (em->disk_bytenr == EXTENT_MAP_HOLE)
ret = RANGE_BOUNDARY_HOLE;
else if (em->flags & EXTENT_FLAG_PREALLOC)
ret = RANGE_BOUNDARY_PREALLOC_EXTENT;
else
ret = RANGE_BOUNDARY_WRITTEN_EXTENT;
free_extent_map(em);
return ret;
}
static int btrfs_zero_range(struct inode *inode,
loff_t offset,
loff_t len,
const int mode)
{
struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
struct extent_map *em;
struct extent_changeset *data_reserved = NULL;
int ret;
u64 alloc_hint = 0;
const u64 sectorsize = fs_info->sectorsize;
u64 alloc_start = round_down(offset, sectorsize);
u64 alloc_end = round_up(offset + len, sectorsize);
u64 bytes_to_reserve = 0;
bool space_reserved = false;
em = btrfs_get_extent(BTRFS_I(inode), NULL, alloc_start,
alloc_end - alloc_start);
if (IS_ERR(em)) {
ret = PTR_ERR(em);
goto out;
}
/*
* Avoid hole punching and extent allocation for some cases. More cases
* could be considered, but these are unlikely common and we keep things
* as simple as possible for now. Also, intentionally, if the target
* range contains one or more prealloc extents together with regular
* extents and holes, we drop all the existing extents and allocate a
* new prealloc extent, so that we get a larger contiguous disk extent.
*/
if (em->start <= alloc_start && (em->flags & EXTENT_FLAG_PREALLOC)) {
const u64 em_end = em->start + em->len;
if (em_end >= offset + len) {
/*
* The whole range is already a prealloc extent,
* do nothing except updating the inode's i_size if
* needed.
*/
free_extent_map(em);
ret = btrfs_fallocate_update_isize(inode, offset + len,
mode);
goto out;
}
/*
* Part of the range is already a prealloc extent, so operate
* only on the remaining part of the range.
*/
alloc_start = em_end;
ASSERT(IS_ALIGNED(alloc_start, sectorsize));
len = offset + len - alloc_start;
offset = alloc_start;
alloc_hint = extent_map_block_start(em) + em->len;
}
free_extent_map(em);
if (BTRFS_BYTES_TO_BLKS(fs_info, offset) ==
BTRFS_BYTES_TO_BLKS(fs_info, offset + len - 1)) {
em = btrfs_get_extent(BTRFS_I(inode), NULL, alloc_start, sectorsize);
if (IS_ERR(em)) {
ret = PTR_ERR(em);
goto out;
}
if (em->flags & EXTENT_FLAG_PREALLOC) {
free_extent_map(em);
ret = btrfs_fallocate_update_isize(inode, offset + len,
mode);
goto out;
}
if (len < sectorsize && em->disk_bytenr != EXTENT_MAP_HOLE) {
free_extent_map(em);
ret = btrfs_truncate_block(BTRFS_I(inode), offset, len,
0);
if (!ret)
ret = btrfs_fallocate_update_isize(inode,
offset + len,
mode);
return ret;
}
free_extent_map(em);
alloc_start = round_down(offset, sectorsize);
alloc_end = alloc_start + sectorsize;
goto reserve_space;
}
alloc_start = round_up(offset, sectorsize);
alloc_end = round_down(offset + len, sectorsize);
/*
* For unaligned ranges, check the pages at the boundaries, they might
* map to an extent, in which case we need to partially zero them, or
* they might map to a hole, in which case we need our allocation range
* to cover them.
*/
if (!IS_ALIGNED(offset, sectorsize)) {
ret = btrfs_zero_range_check_range_boundary(BTRFS_I(inode),
offset);
if (ret < 0)
goto out;
if (ret == RANGE_BOUNDARY_HOLE) {
alloc_start = round_down(offset, sectorsize);
ret = 0;
} else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
ret = btrfs_truncate_block(BTRFS_I(inode), offset, 0, 0);
if (ret)
goto out;
} else {
ret = 0;
}
}
if (!IS_ALIGNED(offset + len, sectorsize)) {
ret = btrfs_zero_range_check_range_boundary(BTRFS_I(inode),
offset + len);
if (ret < 0)
goto out;
if (ret == RANGE_BOUNDARY_HOLE) {
alloc_end = round_up(offset + len, sectorsize);
ret = 0;
} else if (ret == RANGE_BOUNDARY_WRITTEN_EXTENT) {
ret = btrfs_truncate_block(BTRFS_I(inode), offset + len,
0, 1);
if (ret)
goto out;
} else {
ret = 0;
}
}
reserve_space:
if (alloc_start < alloc_end) {
struct extent_state *cached_state = NULL;
const u64 lockstart = alloc_start;
const u64 lockend = alloc_end - 1;
bytes_to_reserve = alloc_end - alloc_start;
ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
bytes_to_reserve);
if (ret < 0)
goto out;
space_reserved = true;
btrfs_punch_hole_lock_range(inode, lockstart, lockend,
&cached_state);
ret = btrfs_qgroup_reserve_data(BTRFS_I(inode), &data_reserved,
alloc_start, bytes_to_reserve);
if (ret) {
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart,
lockend, &cached_state);
goto out;
}
ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
alloc_end - alloc_start,
fs_info->sectorsize,
offset + len, &alloc_hint);
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend,
&cached_state);
/* btrfs_prealloc_file_range releases reserved space on error */
if (ret) {
space_reserved = false;
goto out;
}
}
ret = btrfs_fallocate_update_isize(inode, offset + len, mode);
out:
if (ret && space_reserved)
btrfs_free_reserved_data_space(BTRFS_I(inode), data_reserved,
alloc_start, bytes_to_reserve);
extent_changeset_free(data_reserved);
return ret;
}
static long btrfs_fallocate(struct file *file, int mode,
loff_t offset, loff_t len)
{
struct inode *inode = file_inode(file);
struct extent_state *cached_state = NULL;
struct extent_changeset *data_reserved = NULL;
struct falloc_range *range;
struct falloc_range *tmp;
LIST_HEAD(reserve_list);
u64 cur_offset;
u64 last_byte;
u64 alloc_start;
u64 alloc_end;
u64 alloc_hint = 0;
u64 locked_end;
u64 actual_end = 0;
u64 data_space_needed = 0;
u64 data_space_reserved = 0;
u64 qgroup_reserved = 0;
struct extent_map *em;
int blocksize = BTRFS_I(inode)->root->fs_info->sectorsize;
int ret;
/* Do not allow fallocate in ZONED mode */
if (btrfs_is_zoned(inode_to_fs_info(inode)))
return -EOPNOTSUPP;
alloc_start = round_down(offset, blocksize);
alloc_end = round_up(offset + len, blocksize);
cur_offset = alloc_start;
/* Make sure we aren't being give some crap mode */
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
FALLOC_FL_ZERO_RANGE))
return -EOPNOTSUPP;
if (mode & FALLOC_FL_PUNCH_HOLE)
return btrfs_punch_hole(file, offset, len);
btrfs_inode_lock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
ret = inode_newsize_ok(inode, offset + len);
if (ret)
goto out;
}
ret = file_modified(file);
if (ret)
goto out;
/*
* TODO: Move these two operations after we have checked
* accurate reserved space, or fallocate can still fail but
* with page truncated or size expanded.
*
* But that's a minor problem and won't do much harm BTW.
*/
if (alloc_start > inode->i_size) {
ret = btrfs_cont_expand(BTRFS_I(inode), i_size_read(inode),
alloc_start);
if (ret)
goto out;
} else if (offset + len > inode->i_size) {
/*
* If we are fallocating from the end of the file onward we
* need to zero out the end of the block if i_size lands in the
* middle of a block.
*/
ret = btrfs_truncate_block(BTRFS_I(inode), inode->i_size, 0, 0);
if (ret)
goto out;
}
/*
* We have locked the inode at the VFS level (in exclusive mode) and we
* have locked the i_mmap_lock lock (in exclusive mode). Now before
* locking the file range, flush all dealloc in the range and wait for
* all ordered extents in the range to complete. After this we can lock
* the file range and, due to the previous locking we did, we know there
* can't be more delalloc or ordered extents in the range.
*/
ret = btrfs_wait_ordered_range(BTRFS_I(inode), alloc_start,
alloc_end - alloc_start);
if (ret)
goto out;
if (mode & FALLOC_FL_ZERO_RANGE) {
ret = btrfs_zero_range(inode, offset, len, mode);
btrfs_inode_unlock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
return ret;
}
locked_end = alloc_end - 1;
lock_extent(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
&cached_state);
btrfs_assert_inode_range_clean(BTRFS_I(inode), alloc_start, locked_end);
/* First, check if we exceed the qgroup limit */
while (cur_offset < alloc_end) {
em = btrfs_get_extent(BTRFS_I(inode), NULL, cur_offset,
alloc_end - cur_offset);
if (IS_ERR(em)) {
ret = PTR_ERR(em);
break;
}
last_byte = min(extent_map_end(em), alloc_end);
actual_end = min_t(u64, extent_map_end(em), offset + len);
last_byte = ALIGN(last_byte, blocksize);
if (em->disk_bytenr == EXTENT_MAP_HOLE ||
(cur_offset >= inode->i_size &&
!(em->flags & EXTENT_FLAG_PREALLOC))) {
const u64 range_len = last_byte - cur_offset;
ret = add_falloc_range(&reserve_list, cur_offset, range_len);
if (ret < 0) {
free_extent_map(em);
break;
}
ret = btrfs_qgroup_reserve_data(BTRFS_I(inode),
&data_reserved, cur_offset, range_len);
if (ret < 0) {
free_extent_map(em);
break;
}
qgroup_reserved += range_len;
data_space_needed += range_len;
}
free_extent_map(em);
cur_offset = last_byte;
}
if (!ret && data_space_needed > 0) {
/*
* We are safe to reserve space here as we can't have delalloc
* in the range, see above.
*/
ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
data_space_needed);
if (!ret)
data_space_reserved = data_space_needed;
}
/*
* If ret is still 0, means we're OK to fallocate.
* Or just cleanup the list and exit.
*/
list_for_each_entry_safe(range, tmp, &reserve_list, list) {
if (!ret) {
ret = btrfs_prealloc_file_range(inode, mode,
range->start,
range->len, blocksize,
offset + len, &alloc_hint);
/*
* btrfs_prealloc_file_range() releases space even
* if it returns an error.
*/
data_space_reserved -= range->len;
qgroup_reserved -= range->len;
} else if (data_space_reserved > 0) {
btrfs_free_reserved_data_space(BTRFS_I(inode),
data_reserved, range->start,
range->len);
data_space_reserved -= range->len;
qgroup_reserved -= range->len;
} else if (qgroup_reserved > 0) {
btrfs_qgroup_free_data(BTRFS_I(inode), data_reserved,
range->start, range->len, NULL);
qgroup_reserved -= range->len;
}
list_del(&range->list);
kfree(range);
}
if (ret < 0)
goto out_unlock;
/*
* We didn't need to allocate any more space, but we still extended the
* size of the file so we need to update i_size and the inode item.
*/
ret = btrfs_fallocate_update_isize(inode, actual_end, mode);
out_unlock:
unlock_extent(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
&cached_state);
out:
btrfs_inode_unlock(BTRFS_I(inode), BTRFS_ILOCK_MMAP);
extent_changeset_free(data_reserved);
return ret;
}
/*
* Helper for btrfs_find_delalloc_in_range(). Find a subrange in a given range
* that has unflushed and/or flushing delalloc. There might be other adjacent
* subranges after the one it found, so btrfs_find_delalloc_in_range() keeps
* looping while it gets adjacent subranges, and merging them together.
*/
static bool find_delalloc_subrange(struct btrfs_inode *inode, u64 start, u64 end,
struct extent_state **cached_state,
bool *search_io_tree,
u64 *delalloc_start_ret, u64 *delalloc_end_ret)
{
u64 len = end + 1 - start;
u64 delalloc_len = 0;
struct btrfs_ordered_extent *oe;
u64 oe_start;
u64 oe_end;
/*
* Search the io tree first for EXTENT_DELALLOC. If we find any, it
* means we have delalloc (dirty pages) for which writeback has not
* started yet.
*/
if (*search_io_tree) {
spin_lock(&inode->lock);
if (inode->delalloc_bytes > 0) {
spin_unlock(&inode->lock);
*delalloc_start_ret = start;
delalloc_len = count_range_bits(&inode->io_tree,
delalloc_start_ret, end,
len, EXTENT_DELALLOC, 1,
cached_state);
} else {
spin_unlock(&inode->lock);
}
}
if (delalloc_len > 0) {
/*
* If delalloc was found then *delalloc_start_ret has a sector size
* aligned value (rounded down).
*/
*delalloc_end_ret = *delalloc_start_ret + delalloc_len - 1;
if (*delalloc_start_ret == start) {
/* Delalloc for the whole range, nothing more to do. */
if (*delalloc_end_ret == end)
return true;
/* Else trim our search range for ordered extents. */
start = *delalloc_end_ret + 1;
len = end + 1 - start;
}
} else {
/* No delalloc, future calls don't need to search again. */
*search_io_tree = false;
}
/*
* Now also check if there's any ordered extent in the range.
* We do this because:
*
* 1) When delalloc is flushed, the file range is locked, we clear the
* EXTENT_DELALLOC bit from the io tree and create an extent map and
* an ordered extent for the write. So we might just have been called
* after delalloc is flushed and before the ordered extent completes
* and inserts the new file extent item in the subvolume's btree;
*
* 2) We may have an ordered extent created by flushing delalloc for a
* subrange that starts before the subrange we found marked with
* EXTENT_DELALLOC in the io tree.
*
* We could also use the extent map tree to find such delalloc that is
* being flushed, but using the ordered extents tree is more efficient
* because it's usually much smaller as ordered extents are removed from
* the tree once they complete. With the extent maps, we mau have them
* in the extent map tree for a very long time, and they were either
* created by previous writes or loaded by read operations.
*/
oe = btrfs_lookup_first_ordered_range(inode, start, len);
if (!oe)
return (delalloc_len > 0);
/* The ordered extent may span beyond our search range. */
oe_start = max(oe->file_offset, start);
oe_end = min(oe->file_offset + oe->num_bytes - 1, end);
btrfs_put_ordered_extent(oe);
/* Don't have unflushed delalloc, return the ordered extent range. */
if (delalloc_len == 0) {
*delalloc_start_ret = oe_start;
*delalloc_end_ret = oe_end;
return true;
}
/*
* We have both unflushed delalloc (io_tree) and an ordered extent.
* If the ranges are adjacent returned a combined range, otherwise
* return the leftmost range.
*/
if (oe_start < *delalloc_start_ret) {
if (oe_end < *delalloc_start_ret)
*delalloc_end_ret = oe_end;
*delalloc_start_ret = oe_start;
} else if (*delalloc_end_ret + 1 == oe_start) {
*delalloc_end_ret = oe_end;
}
return true;
}
/*
* Check if there's delalloc in a given range.
*
* @inode: The inode.
* @start: The start offset of the range. It does not need to be
* sector size aligned.
* @end: The end offset (inclusive value) of the search range.
* It does not need to be sector size aligned.
* @cached_state: Extent state record used for speeding up delalloc
* searches in the inode's io_tree. Can be NULL.
* @delalloc_start_ret: Output argument, set to the start offset of the
* subrange found with delalloc (may not be sector size
* aligned).
* @delalloc_end_ret: Output argument, set to he end offset (inclusive value)
* of the subrange found with delalloc.
*
* Returns true if a subrange with delalloc is found within the given range, and
* if so it sets @delalloc_start_ret and @delalloc_end_ret with the start and
* end offsets of the subrange.
*/
bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end,
struct extent_state **cached_state,
u64 *delalloc_start_ret, u64 *delalloc_end_ret)
{
u64 cur_offset = round_down(start, inode->root->fs_info->sectorsize);
u64 prev_delalloc_end = 0;
bool search_io_tree = true;
bool ret = false;
while (cur_offset <= end) {
u64 delalloc_start;
u64 delalloc_end;
bool delalloc;
delalloc = find_delalloc_subrange(inode, cur_offset, end,
cached_state, &search_io_tree,
&delalloc_start,
&delalloc_end);
if (!delalloc)
break;
if (prev_delalloc_end == 0) {
/* First subrange found. */
*delalloc_start_ret = max(delalloc_start, start);
*delalloc_end_ret = delalloc_end;
ret = true;
} else if (delalloc_start == prev_delalloc_end + 1) {
/* Subrange adjacent to the previous one, merge them. */
*delalloc_end_ret = delalloc_end;
} else {
/* Subrange not adjacent to the previous one, exit. */
break;
}
prev_delalloc_end = delalloc_end;
cur_offset = delalloc_end + 1;
cond_resched();
}
return ret;
}
/*
* Check if there's a hole or delalloc range in a range representing a hole (or
* prealloc extent) found in the inode's subvolume btree.
*
* @inode: The inode.
* @whence: Seek mode (SEEK_DATA or SEEK_HOLE).
* @start: Start offset of the hole region. It does not need to be sector
* size aligned.
* @end: End offset (inclusive value) of the hole region. It does not
* need to be sector size aligned.
* @start_ret: Return parameter, used to set the start of the subrange in the
* hole that matches the search criteria (seek mode), if such
* subrange is found (return value of the function is true).
* The value returned here may not be sector size aligned.
*
* Returns true if a subrange matching the given seek mode is found, and if one
* is found, it updates @start_ret with the start of the subrange.
*/
static bool find_desired_extent_in_hole(struct btrfs_inode *inode, int whence,
struct extent_state **cached_state,
u64 start, u64 end, u64 *start_ret)
{
u64 delalloc_start;
u64 delalloc_end;
bool delalloc;
delalloc = btrfs_find_delalloc_in_range(inode, start, end, cached_state,
&delalloc_start, &delalloc_end);
if (delalloc && whence == SEEK_DATA) {
*start_ret = delalloc_start;
return true;
}
if (delalloc && whence == SEEK_HOLE) {
/*
* We found delalloc but it starts after out start offset. So we
* have a hole between our start offset and the delalloc start.
*/
if (start < delalloc_start) {
*start_ret = start;
return true;
}
/*
* Delalloc range starts at our start offset.
* If the delalloc range's length is smaller than our range,
* then it means we have a hole that starts where the delalloc
* subrange ends.
*/
if (delalloc_end < end) {
*start_ret = delalloc_end + 1;
return true;
}
/* There's delalloc for the whole range. */
return false;
}
if (!delalloc && whence == SEEK_HOLE) {
*start_ret = start;
return true;
}
/*
* No delalloc in the range and we are seeking for data. The caller has
* to iterate to the next extent item in the subvolume btree.
*/
return false;
}
static loff_t find_desired_extent(struct file *file, loff_t offset, int whence)
{
struct btrfs_inode *inode = BTRFS_I(file->f_mapping->host);
struct btrfs_file_private *private;
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct extent_state *cached_state = NULL;
struct extent_state **delalloc_cached_state;
const loff_t i_size = i_size_read(&inode->vfs_inode);
const u64 ino = btrfs_ino(inode);
struct btrfs_root *root = inode->root;
struct btrfs_path *path;
struct btrfs_key key;
u64 last_extent_end;
u64 lockstart;
u64 lockend;
u64 start;
int ret;
bool found = false;
if (i_size == 0 || offset >= i_size)
return -ENXIO;
/*
* Quick path. If the inode has no prealloc extents and its number of
* bytes used matches its i_size, then it can not have holes.
*/
if (whence == SEEK_HOLE &&
!(inode->flags & BTRFS_INODE_PREALLOC) &&
inode_get_bytes(&inode->vfs_inode) == i_size)
return i_size;
spin_lock(&inode->lock);
private = file->private_data;
spin_unlock(&inode->lock);
if (private && private->owner_task != current) {
/*
* Not allocated by us, don't use it as its cached state is used
* by the task that allocated it and we don't want neither to
* mess with it nor get incorrect results because it reflects an
* invalid state for the current task.
*/
private = NULL;
} else if (!private) {
private = kzalloc(sizeof(*private), GFP_KERNEL);
/*
* No worries if memory allocation failed.
* The private structure is used only for speeding up multiple
* lseek SEEK_HOLE/DATA calls to a file when there's delalloc,
* so everything will still be correct.
*/
if (private) {
bool free = false;
private->owner_task = current;
spin_lock(&inode->lock);
if (file->private_data)
free = true;
else
file->private_data = private;
spin_unlock(&inode->lock);
if (free) {
kfree(private);
private = NULL;
}
}
}
if (private)
delalloc_cached_state = &private->llseek_cached_state;
else
delalloc_cached_state = NULL;
/*
* offset can be negative, in this case we start finding DATA/HOLE from
* the very start of the file.
*/
start = max_t(loff_t, 0, offset);
lockstart = round_down(start, fs_info->sectorsize);
lockend = round_up(i_size, fs_info->sectorsize);
if (lockend <= lockstart)
lockend = lockstart + fs_info->sectorsize;
lockend--;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = READA_FORWARD;
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = start;
last_extent_end = lockstart;
lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0) {
goto out;
} else if (ret > 0 && path->slots[0] > 0) {
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
path->slots[0]--;
}
while (start < i_size) {
struct extent_buffer *leaf = path->nodes[0];
struct btrfs_file_extent_item *extent;
u64 extent_end;
u8 type;
if (path->slots[0] >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto out;
else if (ret > 0)
break;
leaf = path->nodes[0];
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY)
break;
extent_end = btrfs_file_extent_end(path);
/*
* In the first iteration we may have a slot that points to an
* extent that ends before our start offset, so skip it.
*/
if (extent_end <= start) {
path->slots[0]++;
continue;
}
/* We have an implicit hole, NO_HOLES feature is likely set. */
if (last_extent_end < key.offset) {
u64 search_start = last_extent_end;
u64 found_start;
/*
* First iteration, @start matches @offset and it's
* within the hole.
*/
if (start == offset)
search_start = offset;
found = find_desired_extent_in_hole(inode, whence,
delalloc_cached_state,
search_start,
key.offset - 1,
&found_start);
if (found) {
start = found_start;
break;
}
/*
* Didn't find data or a hole (due to delalloc) in the
* implicit hole range, so need to analyze the extent.
*/
}
extent = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
type = btrfs_file_extent_type(leaf, extent);
/*
* Can't access the extent's disk_bytenr field if this is an
* inline extent, since at that offset, it's where the extent
* data starts.
*/
if (type == BTRFS_FILE_EXTENT_PREALLOC ||
(type == BTRFS_FILE_EXTENT_REG &&
btrfs_file_extent_disk_bytenr(leaf, extent) == 0)) {
/*
* Explicit hole or prealloc extent, search for delalloc.
* A prealloc extent is treated like a hole.
*/
u64 search_start = key.offset;
u64 found_start;
/*
* First iteration, @start matches @offset and it's
* within the hole.
*/
if (start == offset)
search_start = offset;
found = find_desired_extent_in_hole(inode, whence,
delalloc_cached_state,
search_start,
extent_end - 1,
&found_start);
if (found) {
start = found_start;
break;
}
/*
* Didn't find data or a hole (due to delalloc) in the
* implicit hole range, so need to analyze the next
* extent item.
*/
} else {
/*
* Found a regular or inline extent.
* If we are seeking for data, adjust the start offset
* and stop, we're done.
*/
if (whence == SEEK_DATA) {
start = max_t(u64, key.offset, offset);
found = true;
break;
}
/*
* Else, we are seeking for a hole, check the next file
* extent item.
*/
}
start = extent_end;
last_extent_end = extent_end;
path->slots[0]++;
if (fatal_signal_pending(current)) {
ret = -EINTR;
goto out;
}
cond_resched();
}
/* We have an implicit hole from the last extent found up to i_size. */
if (!found && start < i_size) {
found = find_desired_extent_in_hole(inode, whence,
delalloc_cached_state, start,
i_size - 1, &start);
if (!found)
start = i_size;
}
out:
unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
btrfs_free_path(path);
if (ret < 0)
return ret;
if (whence == SEEK_DATA && start >= i_size)
return -ENXIO;
return min_t(loff_t, start, i_size);
}
static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
{
struct inode *inode = file->f_mapping->host;
switch (whence) {
default:
return generic_file_llseek(file, offset, whence);
case SEEK_DATA:
case SEEK_HOLE:
btrfs_inode_lock(BTRFS_I(inode), BTRFS_ILOCK_SHARED);
offset = find_desired_extent(file, offset, whence);
btrfs_inode_unlock(BTRFS_I(inode), BTRFS_ILOCK_SHARED);
break;
}
if (offset < 0)
return offset;
return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
}
static int btrfs_file_open(struct inode *inode, struct file *filp)
{
int ret;
filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
ret = fsverity_file_open(inode, filp);
if (ret)
return ret;
return generic_file_open(inode, filp);
}
static ssize_t btrfs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
ssize_t ret = 0;
if (iocb->ki_flags & IOCB_DIRECT) {
ret = btrfs_direct_read(iocb, to);
if (ret < 0 || !iov_iter_count(to) ||
iocb->ki_pos >= i_size_read(file_inode(iocb->ki_filp)))
return ret;
}
return filemap_read(iocb, to, ret);
}
const struct file_operations btrfs_file_operations = {
.llseek = btrfs_file_llseek,
.read_iter = btrfs_file_read_iter,
.splice_read = filemap_splice_read,
.write_iter = btrfs_file_write_iter,
.splice_write = iter_file_splice_write,
.mmap = btrfs_file_mmap,
.open = btrfs_file_open,
.release = btrfs_release_file,
.get_unmapped_area = thp_get_unmapped_area,
.fsync = btrfs_sync_file,
.fallocate = btrfs_fallocate,
.unlocked_ioctl = btrfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = btrfs_compat_ioctl,
#endif
.remap_file_range = btrfs_remap_file_range,
.fop_flags = FOP_BUFFER_RASYNC | FOP_BUFFER_WASYNC,
};
int btrfs_fdatawrite_range(struct btrfs_inode *inode, loff_t start, loff_t end)
{
struct address_space *mapping = inode->vfs_inode.i_mapping;
int ret;
/*
* So with compression we will find and lock a dirty page and clear the
* first one as dirty, setup an async extent, and immediately return
* with the entire range locked but with nobody actually marked with
* writeback. So we can't just filemap_write_and_wait_range() and
* expect it to work since it will just kick off a thread to do the
* actual work. So we need to call filemap_fdatawrite_range _again_
* since it will wait on the page lock, which won't be unlocked until
* after the pages have been marked as writeback and so we're good to go
* from there. We have to do this otherwise we'll miss the ordered
* extents and that results in badness. Please Josef, do not think you
* know better and pull this out at some point in the future, it is
* right and you are wrong.
*/
ret = filemap_fdatawrite_range(mapping, start, end);
if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags))
ret = filemap_fdatawrite_range(mapping, start, end);
return ret;
}
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