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626e9f41f7
linux/fs/btrfs/file.c
Filipe Manana 626e9f41f7 btrfs: fix race leading to unpersisted data and metadata on fsync 
When doing a fast fsync on a file, there is a race which can result in the
fsync returning success to user space without logging the inode and without
durably persisting new data.

The following example shows one possible scenario for this:

   $ mkfs.btrfs -f /dev/sdc
   $ mount /dev/sdc /mnt

   $ touch /mnt/bar
   $ xfs_io -f -c "pwrite -S 0xab 0 1M" -c "fsync" /mnt/baz

   # Now we have:
   # file bar == inode 257
   # file baz == inode 258

   $ mv /mnt/baz /mnt/foo

   # Now we have:
   # file bar == inode 257
   # file foo == inode 258

   $ xfs_io -c "pwrite -S 0xcd 0 1M" /mnt/foo

   # fsync bar before foo, it is important to trigger the race.
   $ xfs_io -c "fsync" /mnt/bar
   $ xfs_io -c "fsync" /mnt/foo

   # After this:
   # inode 257, file bar, is empty
   # inode 258, file foo, has 1M filled with 0xcd

   <power failure>

   # Replay the log:
   $ mount /dev/sdc /mnt

   # After this point file foo should have 1M filled with 0xcd and not 0xab

The following steps explain how the race happens:

1) Before the first fsync of inode 258, when it has the "baz" name, its
   ->logged_trans is 0, ->last_sub_trans is 0 and ->last_log_commit is -1.
   The inode also has the full sync flag set;

2) After the first fsync, we set inode 258 ->logged_trans to 6, which is
   the generation of the current transaction, and set ->last_log_commit
   to 0, which is the current value of ->last_sub_trans (done at
   btrfs_log_inode()).

   The full sync flag is cleared from the inode during the fsync.

   The log sub transaction that was committed had an ID of 0 and when we
   synced the log, at btrfs_sync_log(), we incremented root->log_transid
   from 0 to 1;

3) During the rename:

   We update inode 258, through btrfs_update_inode(), and that causes its
   ->last_sub_trans to be set to 1 (the current log transaction ID), and
   ->last_log_commit remains with a value of 0.

   After updating inode 258, because we have previously logged the inode
   in the previous fsync, we log again the inode through the call to
   btrfs_log_new_name(). This results in updating the inode's
   ->last_log_commit from 0 to 1 (the current value of its
   ->last_sub_trans).

   The ->last_sub_trans of inode 257 is updated to 1, which is the ID of
   the next log transaction;

4) Then a buffered write against inode 258 is made. This leaves the value
   of ->last_sub_trans as 1 (the ID of the current log transaction, stored
   at root->log_transid);

5) Then an fsync against inode 257 (or any other inode other than 258),
   happens. This results in committing the log transaction with ID 1,
   which results in updating root->last_log_commit to 1 and bumping
   root->log_transid from 1 to 2;

6) Then an fsync against inode 258 starts. We flush delalloc and wait only
   for writeback to complete, since the full sync flag is not set in the
   inode's runtime flags - we do not wait for ordered extents to complete.

   Then, at btrfs_sync_file(), we call btrfs_inode_in_log() before the
   ordered extent completes. The call returns true:

     static inline bool btrfs_inode_in_log(...)
     {
         bool ret = false;

         spin_lock(&inode->lock);
         if (inode->logged_trans == generation &&
             inode->last_sub_trans <= inode->last_log_commit &&
             inode->last_sub_trans <= inode->root->last_log_commit)
                 ret = true;
         spin_unlock(&inode->lock);
         return ret;
     }

   generation has a value of 6 (fs_info->generation), ->logged_trans also
   has a value of 6 (set when we logged the inode during the first fsync
   and when logging it during the rename), ->last_sub_trans has a value
   of 1, set during the rename (step 3), ->last_log_commit also has a
   value of 1 (set in step 3) and root->last_log_commit has a value of 1,
   which was set in step 5 when fsyncing inode 257.

   As a consequence we don't log the inode, any new extents and do not
   sync the log, resulting in a data loss if a power failure happens
   after the fsync and before the current transaction commits.
   Also, because we do not log the inode, after a power failure the mtime
   and ctime of the inode do not match those we had before.

   When the ordered extent completes before we call btrfs_inode_in_log(),
   then the call returns false and we log the inode and sync the log,
   since at the end of ordered extent completion we update the inode and
   set ->last_sub_trans to 2 (the value of root->log_transid) and
   ->last_log_commit to 1.

This problem is found after removing the check for the emptiness of the
inode's list of modified extents in the recent commit 209ecbb858
("btrfs: remove stale comment and logic from btrfs_inode_in_log()"),
added in the 5.13 merge window. However checking the emptiness of the
list is not really the way to solve this problem, and was never intended
to, because while that solves the problem for COW writes, the problem
persists for NOCOW writes because in that case the list is always empty.

In the case of NOCOW writes, even though we wait for the writeback to
complete before returning from btrfs_sync_file(), we end up not logging
the inode, which has a new mtime/ctime, and because we don't sync the log,
we never issue disk barriers (send REQ_PREFLUSH to the device) since that
only happens when we sync the log (when we write super blocks at
btrfs_sync_log()). So effectively, for a NOCOW case, when we return from
btrfs_sync_file() to user space, we are not guaranteeing that the data is
durably persisted on disk.

Also, while the example above uses a rename exchange to show how the
problem happens, it is not the only way to trigger it. An alternative
could be adding a new hard link to inode 258, since that also results
in calling btrfs_log_new_name() and updating the inode in the log.
An example reproducer using the addition of a hard link instead of a
rename operation:

  $ mkfs.btrfs -f /dev/sdc
  $ mount /dev/sdc /mnt

  $ touch /mnt/bar
  $ xfs_io -f -c "pwrite -S 0xab 0 1M" -c "fsync" /mnt/foo

  $ ln /mnt/foo /mnt/foo_link
  $ xfs_io -c "pwrite -S 0xcd 0 1M" /mnt/foo

  $ xfs_io -c "fsync" /mnt/bar
  $ xfs_io -c "fsync" /mnt/foo

  <power failure>

  # Replay the log:
  $ mount /dev/sdc /mnt

  # After this point file foo often has 1M filled with 0xab and not 0xcd

The reasons leading to the final fsync of file foo, inode 258, not
persisting the new data are the same as for the previous example with
a rename operation.

So fix by never skipping logging and log syncing when there are still any
ordered extents in flight. To avoid making the conditional if statement
that checks if logging an inode is needed harder to read, place all the
logic into an helper function with separate if statements to make it more
manageable and easier to read.

A test case for fstests will follow soon.

For NOCOW writes, the problem existed before commit b5e6c3e170
("btrfs: always wait on ordered extents at fsync time"), introduced in
kernel 4.19, then it went away with that commit since we started to always
wait for ordered extent completion before logging.

The problem came back again once the fast fsync path was changed again to
avoid waiting for ordered extent completion, in commit 487781796d
("btrfs: make fast fsyncs wait only for writeback"), added in kernel 5.10.

However, for COW writes, the race only happens after the recent
commit 209ecbb858 ("btrfs: remove stale comment and logic from
btrfs_inode_in_log()"), introduced in the 5.13 merge window. For NOCOW
writes, the bug existed before that commit. So tag 5.10+ as the release
for stable backports.

CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-28 20:09:45 +02:00

3708 lines
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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 "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "print-tree.h"
#include "tree-log.h"
#include "locking.h"
#include "volumes.h"
#include "qgroup.h"
#include "compression.h"
#include "delalloc-space.h"
#include "reflink.h"
static struct kmem_cache *btrfs_inode_defrag_cachep;
/*
* when auto defrag is enabled we
* queue up these defrag structs to remember which
* inodes need defragging passes
*/
struct inode_defrag {
struct rb_node rb_node;
/* objectid */
u64 ino;
/*
* transid where the defrag was added, we search for
* extents newer than this
*/
u64 transid;
/* root objectid */
u64 root;
/* last offset we were able to defrag */
u64 last_offset;
/* if we've wrapped around back to zero once already */
int cycled;
};
static int __compare_inode_defrag(struct inode_defrag *defrag1,
struct inode_defrag *defrag2)
{
if (defrag1->root > defrag2->root)
return 1;
else if (defrag1->root < defrag2->root)
return -1;
else if (defrag1->ino > defrag2->ino)
return 1;
else if (defrag1->ino < defrag2->ino)
return -1;
else
return 0;
}
/* pop a record for an inode into the defrag tree. The lock
* must be held already
*
* If you're inserting a record for an older transid than an
* existing record, the transid already in the tree is lowered
*
* If an existing record is found the defrag item you
* pass in is freed
*/
static int __btrfs_add_inode_defrag(struct btrfs_inode *inode,
struct inode_defrag *defrag)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct inode_defrag *entry;
struct rb_node **p;
struct rb_node *parent = NULL;
int ret;
p = &fs_info->defrag_inodes.rb_node;
while (*p) {
parent = *p;
entry = rb_entry(parent, struct inode_defrag, rb_node);
ret = __compare_inode_defrag(defrag, entry);
if (ret < 0)
p = &parent->rb_left;
else if (ret > 0)
p = &parent->rb_right;
else {
/* if we're reinserting an entry for
* an old defrag run, make sure to
* lower the transid of our existing record
*/
if (defrag->transid < entry->transid)
entry->transid = defrag->transid;
if (defrag->last_offset > entry->last_offset)
entry->last_offset = defrag->last_offset;
return -EEXIST;
}
}
set_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags);
rb_link_node(&defrag->rb_node, parent, p);
rb_insert_color(&defrag->rb_node, &fs_info->defrag_inodes);
return 0;
}
static inline int __need_auto_defrag(struct btrfs_fs_info *fs_info)
{
if (!btrfs_test_opt(fs_info, AUTO_DEFRAG))
return 0;
if (btrfs_fs_closing(fs_info))
return 0;
return 1;
}
/*
* insert a defrag record for this inode if auto defrag is
* enabled
*/
int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
struct btrfs_inode *inode)
{
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
struct inode_defrag *defrag;
u64 transid;
int ret;
if (!__need_auto_defrag(fs_info))
return 0;
if (test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags))
return 0;
if (trans)
transid = trans->transid;
else
transid = inode->root->last_trans;
defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
if (!defrag)
return -ENOMEM;
defrag->ino = btrfs_ino(inode);
defrag->transid = transid;
defrag->root = root->root_key.objectid;
spin_lock(&fs_info->defrag_inodes_lock);
if (!test_bit(BTRFS_INODE_IN_DEFRAG, &inode->runtime_flags)) {
/*
* If we set IN_DEFRAG flag and evict the inode from memory,
* and then re-read this inode, this new inode doesn't have
* IN_DEFRAG flag. At the case, we may find the existed defrag.
*/
ret = __btrfs_add_inode_defrag(inode, defrag);
if (ret)
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
} else {
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
}
spin_unlock(&fs_info->defrag_inodes_lock);
return 0;
}
/*
* Requeue the defrag object. If there is a defrag object that points to
* the same inode in the tree, we will merge them together (by
* __btrfs_add_inode_defrag()) and free the one that we want to requeue.
*/
static void btrfs_requeue_inode_defrag(struct btrfs_inode *inode,
struct inode_defrag *defrag)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
int ret;
if (!__need_auto_defrag(fs_info))
goto out;
/*
* Here we don't check the IN_DEFRAG flag, because we need merge
* them together.
*/
spin_lock(&fs_info->defrag_inodes_lock);
ret = __btrfs_add_inode_defrag(inode, defrag);
spin_unlock(&fs_info->defrag_inodes_lock);
if (ret)
goto out;
return;
out:
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
}
/*
* pick the defragable inode that we want, if it doesn't exist, we will get
* the next one.
*/
static struct inode_defrag *
btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
{
struct inode_defrag *entry = NULL;
struct inode_defrag tmp;
struct rb_node *p;
struct rb_node *parent = NULL;
int ret;
tmp.ino = ino;
tmp.root = root;
spin_lock(&fs_info->defrag_inodes_lock);
p = fs_info->defrag_inodes.rb_node;
while (p) {
parent = p;
entry = rb_entry(parent, struct inode_defrag, rb_node);
ret = __compare_inode_defrag(&tmp, entry);
if (ret < 0)
p = parent->rb_left;
else if (ret > 0)
p = parent->rb_right;
else
goto out;
}
if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
parent = rb_next(parent);
if (parent)
entry = rb_entry(parent, struct inode_defrag, rb_node);
else
entry = NULL;
}
out:
if (entry)
rb_erase(parent, &fs_info->defrag_inodes);
spin_unlock(&fs_info->defrag_inodes_lock);
return entry;
}
void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
{
struct inode_defrag *defrag;
struct rb_node *node;
spin_lock(&fs_info->defrag_inodes_lock);
node = rb_first(&fs_info->defrag_inodes);
while (node) {
rb_erase(node, &fs_info->defrag_inodes);
defrag = rb_entry(node, struct inode_defrag, rb_node);
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
cond_resched_lock(&fs_info->defrag_inodes_lock);
node = rb_first(&fs_info->defrag_inodes);
}
spin_unlock(&fs_info->defrag_inodes_lock);
}
#define BTRFS_DEFRAG_BATCH 1024
static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
struct inode_defrag *defrag)
{
struct btrfs_root *inode_root;
struct inode *inode;
struct btrfs_ioctl_defrag_range_args range;
int num_defrag;
int ret;
/* get the inode */
inode_root = btrfs_get_fs_root(fs_info, defrag->root, true);
if (IS_ERR(inode_root)) {
ret = PTR_ERR(inode_root);
goto cleanup;
}
inode = btrfs_iget(fs_info->sb, defrag->ino, inode_root);
btrfs_put_root(inode_root);
if (IS_ERR(inode)) {
ret = PTR_ERR(inode);
goto cleanup;
}
/* do a chunk of defrag */
clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
memset(&range, 0, sizeof(range));
range.len = (u64)-1;
range.start = defrag->last_offset;
sb_start_write(fs_info->sb);
num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
BTRFS_DEFRAG_BATCH);
sb_end_write(fs_info->sb);
/*
* if we filled the whole defrag batch, there
* must be more work to do. Queue this defrag
* again
*/
if (num_defrag == BTRFS_DEFRAG_BATCH) {
defrag->last_offset = range.start;
btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
} else if (defrag->last_offset && !defrag->cycled) {
/*
* we didn't fill our defrag batch, but
* we didn't start at zero. Make sure we loop
* around to the start of the file.
*/
defrag->last_offset = 0;
defrag->cycled = 1;
btrfs_requeue_inode_defrag(BTRFS_I(inode), defrag);
} else {
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
}
iput(inode);
return 0;
cleanup:
kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
return ret;
}
/*
* run through the list of inodes in the FS that need
* defragging
*/
int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
{
struct inode_defrag *defrag;
u64 first_ino = 0;
u64 root_objectid = 0;
atomic_inc(&fs_info->defrag_running);
while (1) {
/* Pause the auto defragger. */
if (test_bit(BTRFS_FS_STATE_REMOUNTING,
&fs_info->fs_state))
break;
if (!__need_auto_defrag(fs_info))
break;
/* find an inode to defrag */
defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
first_ino);
if (!defrag) {
if (root_objectid || first_ino) {
root_objectid = 0;
first_ino = 0;
continue;
} else {
break;
}
}
first_ino = defrag->ino + 1;
root_objectid = defrag->root;
__btrfs_run_defrag_inode(fs_info, defrag);
}
atomic_dec(&fs_info->defrag_running);
/*
* during unmount, we use the transaction_wait queue to
* wait for the defragger to stop
*/
wake_up(&fs_info->transaction_wait);
return 0;
}
/* 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 = iov_iter_copy_from_user_atomic(page, i, offset, count);
/* 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 (!PageUptodate(page) && copied < count)
copied = 0;
iov_iter_advance(i, copied);
write_bytes -= copied;
total_copied += copied;
/* Return to btrfs_file_write_iter to fault page */
if (unlikely(copied == 0))
break;
if (copied < PAGE_SIZE - offset) {
offset += copied;
} else {
pg++;
offset = 0;
}
}
return total_copied;
}
/*
* unlocks pages after btrfs_file_write is done with them
*/
static void btrfs_drop_pages(struct page **pages, size_t num_pages)
{
size_t i;
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()
*/
ClearPageChecked(pages[i]);
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 err = 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);
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,
0, 0, cached);
err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
extra_bits, cached);
if (err)
return err;
for (i = 0; i < num_pages; i++) {
struct page *p = pages[i];
SetPageUptodate(p);
ClearPageChecked(p);
set_page_dirty(p);
}
/*
* 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 drops all the extents in the cache that intersect the range
* [start, end]. Existing extents are split as required.
*/
void btrfs_drop_extent_cache(struct btrfs_inode *inode, u64 start, u64 end,
int skip_pinned)
{
struct extent_map *em;
struct extent_map *split = NULL;
struct extent_map *split2 = NULL;
struct extent_map_tree *em_tree = &inode->extent_tree;
u64 len = end - start + 1;
u64 gen;
int ret;
int testend = 1;
unsigned long flags;
int compressed = 0;
bool modified;
WARN_ON(end < start);
if (end == (u64)-1) {
len = (u64)-1;
testend = 0;
}
while (1) {
int no_splits = 0;
modified = false;
if (!split)
split = alloc_extent_map();
if (!split2)
split2 = alloc_extent_map();
if (!split || !split2)
no_splits = 1;
write_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, start, len);
if (!em) {
write_unlock(&em_tree->lock);
break;
}
flags = em->flags;
gen = em->generation;
if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
if (testend && em->start + em->len >= start + len) {
free_extent_map(em);
write_unlock(&em_tree->lock);
break;
}
start = em->start + em->len;
if (testend)
len = start + len - (em->start + em->len);
free_extent_map(em);
write_unlock(&em_tree->lock);
continue;
}
compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
clear_bit(EXTENT_FLAG_LOGGING, &flags);
modified = !list_empty(&em->list);
if (no_splits)
goto next;
if (em->start < start) {
split->start = em->start;
split->len = start - em->start;
if (em->block_start < EXTENT_MAP_LAST_BYTE) {
split->orig_start = em->orig_start;
split->block_start = em->block_start;
if (compressed)
split->block_len = em->block_len;
else
split->block_len = split->len;
split->orig_block_len = max(split->block_len,
em->orig_block_len);
split->ram_bytes = em->ram_bytes;
} else {
split->orig_start = split->start;
split->block_len = 0;
split->block_start = em->block_start;
split->orig_block_len = 0;
split->ram_bytes = split->len;
}
split->generation = gen;
split->flags = flags;
split->compress_type = em->compress_type;
replace_extent_mapping(em_tree, em, split, modified);
free_extent_map(split);
split = split2;
split2 = NULL;
}
if (testend && em->start + em->len > start + len) {
u64 diff = start + len - em->start;
split->start = start + len;
split->len = em->start + em->len - (start + len);
split->flags = flags;
split->compress_type = em->compress_type;
split->generation = gen;
if (em->block_start < EXTENT_MAP_LAST_BYTE) {
split->orig_block_len = max(em->block_len,
em->orig_block_len);
split->ram_bytes = em->ram_bytes;
if (compressed) {
split->block_len = em->block_len;
split->block_start = em->block_start;
split->orig_start = em->orig_start;
} else {
split->block_len = split->len;
split->block_start = em->block_start
+ diff;
split->orig_start = em->orig_start;
}
} else {
split->ram_bytes = split->len;
split->orig_start = split->start;
split->block_len = 0;
split->block_start = em->block_start;
split->orig_block_len = 0;
}
if (extent_map_in_tree(em)) {
replace_extent_mapping(em_tree, em, split,
modified);
} else {
ret = add_extent_mapping(em_tree, split,
modified);
ASSERT(ret == 0); /* Logic error */
}
free_extent_map(split);
split = NULL;
}
next:
if (extent_map_in_tree(em))
remove_extent_mapping(em_tree, em);
write_unlock(&em_tree->lock);
/* once for us */
free_extent_map(em);
/* once for the tree*/
free_extent_map(em);
}
if (split)
free_extent_map(split);
if (split2)
free_extent_map(split2);
}
/*
* 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_ref ref = { 0 };
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;
int leafs_visited = 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_cache(inode, args->start, args->end - 1, 0);
if (args->start >= inode->disk_i_size && !args->replace_extent)
modify_tree = 0;
update_refs = (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
root == fs_info->tree_root);
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;
leafs_visited++;
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;
}
leafs_visited++;
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(leaf);
if (update_refs && disk_bytenr > 0) {
btrfs_init_generic_ref(&ref,
BTRFS_ADD_DELAYED_REF,
disk_bytenr, num_bytes, 0);
btrfs_init_data_ref(&ref,
root->root_key.objectid,
new_key.objectid,
args->start - extent_offset);
ret = btrfs_inc_extent_ref(trans, &ref);
BUG_ON(ret); /* -ENOMEM */
}
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(fs_info, 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(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(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) {
btrfs_init_generic_ref(&ref,
BTRFS_DROP_DELAYED_REF,
disk_bytenr, num_bytes, 0);
btrfs_init_data_ref(&ref,
root->root_key.objectid,
key.objectid,
key.offset - extent_offset);
ret = btrfs_free_extent(trans, &ref);
BUG_ON(ret); /* -ENOMEM */
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 && leafs_visited == 1 &&
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]++;
}
setup_items_for_insert(root, path, &key,
&args->extent_item_size, 1);
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_fs_info *fs_info = trans->fs_info;
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;
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(fs_info, 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(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(fs_info, 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(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(leaf);
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, bytenr,
num_bytes, 0);
btrfs_init_data_ref(&ref, root->root_key.objectid, ino,
orig_offset);
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;
btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
num_bytes, 0);
btrfs_init_data_ref(&ref, root->root_key.objectid, ino, orig_offset);
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(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(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 0;
}
/*
* 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)
{
int ret = 0;
if (((pos & (PAGE_SIZE - 1)) || force_uptodate) &&
!PageUptodate(page)) {
ret = btrfs_readpage(NULL, page);
if (ret)
return ret;
lock_page(page);
if (!PageUptodate(page)) {
unlock_page(page);
return -EIO;
}
if (page->mapping != inode->i_mapping) {
unlock_page(page);
return -EAGAIN;
}
}
return 0;
}
/*
* 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)
{
int i;
unsigned long index = pos >> PAGE_SHIFT;
gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
int err = 0;
int faili;
for (i = 0; i < num_pages; i++) {
again:
pages[i] = find_or_create_page(inode->i_mapping, index + i,
mask | __GFP_WRITE);
if (!pages[i]) {
faili = i - 1;
err = -ENOMEM;
goto fail;
}
err = set_page_extent_mapped(pages[i]);
if (err < 0) {
faili = i;
goto fail;
}
if (i == 0)
err = prepare_uptodate_page(inode, pages[i], pos,
force_uptodate);
if (!err && i == num_pages - 1)
err = prepare_uptodate_page(inode, pages[i],
pos + write_bytes, false);
if (err) {
put_page(pages[i]);
if (err == -EAGAIN) {
err = 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 err;
}
/*
* 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,
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;
lock_extent_bits(&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_cached(&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, 1);
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;
}
static int check_can_nocow(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;
u64 lockstart, lockend;
u64 num_bytes;
int ret;
if (!(inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
return 0;
if (!nowait && !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) {
struct btrfs_ordered_extent *ordered;
if (!try_lock_extent(&inode->io_tree, lockstart, lockend))
return -EAGAIN;
ordered = btrfs_lookup_ordered_range(inode, lockstart,
num_bytes);
if (ordered) {
btrfs_put_ordered_extent(ordered);
ret = -EAGAIN;
goto out_unlock;
}
} else {
btrfs_lock_and_flush_ordered_range(inode, lockstart,
lockend, NULL);
}
ret = can_nocow_extent(&inode->vfs_inode, lockstart, &num_bytes,
NULL, NULL, NULL, false);
if (ret <= 0) {
ret = 0;
if (!nowait)
btrfs_drew_write_unlock(&root->snapshot_lock);
} else {
*write_bytes = min_t(size_t, *write_bytes ,
num_bytes - pos + lockstart);
}
out_unlock:
unlock_extent(&inode->io_tree, lockstart, lockend);
return ret;
}
static int check_nocow_nolock(struct btrfs_inode *inode, loff_t pos,
size_t *write_bytes)
{
return check_can_nocow(inode, pos, write_bytes, true);
}
/*
* 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 and update @write_bytes if we can do nocow write
* 0 if we can't do nocow write
* -EAGAIN if we can't get the needed lock or there are ordered extents
* for * (nowait == true) case
* <0 if other error happened
*
* NOTE: Callers need to release the lock by btrfs_check_nocow_unlock().
*/
int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
size_t *write_bytes)
{
return check_can_nocow(inode, pos, write_bytes, false);
}
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;
if (IS_NOCMTIME(inode))
return;
now = current_time(inode);
if (!timespec64_equal(&inode->i_mtime, &now))
inode->i_mtime = now;
if (!timespec64_equal(&inode->i_ctime, &now))
inode->i_ctime = now;
if (IS_I_VERSION(inode))
inode_inc_iversion(inode);
}
static 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 = btrfs_sb(inode->i_sb);
loff_t pos = iocb->ki_pos;
int ret;
loff_t oldsize;
loff_t start_pos;
if (iocb->ki_flags & IOCB_NOWAIT) {
size_t nocow_bytes = count;
/* We will allocate space in case nodatacow is not set, so bail */
if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes) <= 0)
return -EAGAIN;
/*
* There are holes in the range or parts of the range that must
* be COWed (shared extents, RO block groups, etc), so just bail
* out.
*/
if (nocow_bytes < count)
return -EAGAIN;
}
current->backing_dev_info = inode_to_bdi(inode);
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) {
current->backing_dev_info = NULL;
return ret;
}
}
return 0;
}
static noinline 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 = btrfs_sb(inode->i_sb);
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;
if (iocb->ki_flags & IOCB_NOWAIT)
ilock_flags |= BTRFS_ILOCK_TRY;
ret = btrfs_inode_lock(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(iov_iter_fault_in_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);
if (ret < 0) {
/*
* If we don't have to COW at the offset, reserve
* metadata only. write_bytes may get smaller than
* requested here.
*/
if (btrfs_check_nocow_lock(BTRFS_I(inode), pos,
&write_bytes) > 0)
only_release_metadata = true;
else
break;
}
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);
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));
break;
}
release_bytes = reserve_bytes;
again:
/*
* 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);
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, &cached_state);
if (extents_locked < 0) {
if (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_cached(&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(pages, num_pages);
break;
}
release_bytes = 0;
if (only_release_metadata)
btrfs_check_nocow_unlock(BTRFS_I(inode));
btrfs_drop_pages(pages, num_pages);
cond_resched();
balance_dirty_pages_ratelimited(inode->i_mapping);
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(inode, ilock_flags);
return num_written ? num_written : ret;
}
static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
const struct iov_iter *iter, loff_t offset)
{
const u32 blocksize_mask = fs_info->sectorsize - 1;
if (offset & blocksize_mask)
return -EINVAL;
if (iov_iter_alignment(iter) & blocksize_mask)
return -EINVAL;
return 0;
}
static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
loff_t pos;
ssize_t written = 0;
ssize_t written_buffered;
loff_t endbyte;
ssize_t err;
unsigned int ilock_flags = 0;
struct iomap_dio *dio = NULL;
if (iocb->ki_flags & IOCB_NOWAIT)
ilock_flags |= BTRFS_ILOCK_TRY;
/* If the write DIO is within EOF, use a shared lock */
if (iocb->ki_pos + iov_iter_count(from) <= i_size_read(inode))
ilock_flags |= BTRFS_ILOCK_SHARED;
relock:
err = btrfs_inode_lock(inode, ilock_flags);
if (err < 0)
return err;
err = generic_write_checks(iocb, from);
if (err <= 0) {
btrfs_inode_unlock(inode, ilock_flags);
return err;
}
err = btrfs_write_check(iocb, from, err);
if (err < 0) {
btrfs_inode_unlock(inode, ilock_flags);
goto out;
}
pos = iocb->ki_pos;
/*
* Re-check since file size may have changed just before taking the
* lock or pos may have changed because of O_APPEND in generic_write_check()
*/
if ((ilock_flags & BTRFS_ILOCK_SHARED) &&
pos + iov_iter_count(from) > i_size_read(inode)) {
btrfs_inode_unlock(inode, ilock_flags);
ilock_flags &= ~BTRFS_ILOCK_SHARED;
goto relock;
}
if (check_direct_IO(fs_info, from, pos)) {
btrfs_inode_unlock(inode, ilock_flags);
goto buffered;
}
dio = __iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
0);
btrfs_inode_unlock(inode, ilock_flags);
if (IS_ERR_OR_NULL(dio)) {
err = PTR_ERR_OR_ZERO(dio);
if (err < 0 && err != -ENOTBLK)
goto out;
} else {
written = iomap_dio_complete(dio);
}
if (written < 0 || !iov_iter_count(from)) {
err = written;
goto out;
}
buffered:
pos = iocb->ki_pos;
written_buffered = btrfs_buffered_write(iocb, from);
if (written_buffered < 0) {
err = written_buffered;
goto out;
}
/*
* Ensure all data is persisted. We want the next direct IO read to be
* able to read what was just written.
*/
endbyte = pos + written_buffered - 1;
err = btrfs_fdatawrite_range(inode, pos, endbyte);
if (err)
goto out;
err = filemap_fdatawait_range(inode->i_mapping, pos, endbyte);
if (err)
goto out;
written += written_buffered;
iocb->ki_pos = pos + written_buffered;
invalidate_mapping_pages(file->f_mapping, pos >> PAGE_SHIFT,
endbyte >> PAGE_SHIFT);
out:
return written ? written : err;
}
static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct btrfs_inode *inode = BTRFS_I(file_inode(file));
ssize_t num_written = 0;
const bool sync = iocb->ki_flags & IOCB_DSYNC;
/*
* 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 (test_bit(BTRFS_FS_STATE_ERROR, &inode->root->fs_info->fs_state))
return -EROFS;
if (!(iocb->ki_flags & IOCB_DIRECT) &&
(iocb->ki_flags & IOCB_NOWAIT))
return -EOPNOTSUPP;
if (sync)
atomic_inc(&inode->sync_writers);
if (iocb->ki_flags & IOCB_DIRECT)
num_written = btrfs_direct_write(iocb, from);
else
num_written = btrfs_buffered_write(iocb, from);
btrfs_set_inode_last_sub_trans(inode);
if (num_written > 0)
num_written = generic_write_sync(iocb, num_written);
if (sync)
atomic_dec(&inode->sync_writers);
current->backing_dev_info = NULL;
return num_written;
}
int btrfs_release_file(struct inode *inode, struct file *filp)
{
struct btrfs_file_private *private = filp->private_data;
if (private && private->filldir_buf)
kfree(private->filldir_buf);
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 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);
atomic_inc(&BTRFS_I(inode)->sync_writers);
ret = btrfs_fdatawrite_range(inode, start, end);
atomic_dec(&BTRFS_I(inode)->sync_writers);
blk_finish_plug(&plug);
return ret;
}
static inline bool skip_inode_logging(const struct btrfs_log_ctx *ctx)
{
struct btrfs_inode *inode = BTRFS_I(ctx->inode);
struct btrfs_fs_info *fs_info = inode->root->fs_info;
if (btrfs_inode_in_log(inode, fs_info->generation) &&
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 <= fs_info->last_trans_committed &&
(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 inode *inode = d_inode(dentry);
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_trans_handle *trans;
struct btrfs_log_ctx ctx;
int ret = 0, err;
u64 len;
bool full_sync;
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;
btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
atomic_inc(&root->log_batch);
/*
* 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.
*/
full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
&BTRFS_I(inode)->runtime_flags);
/*
* 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) {
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
goto out;
}
/*
* 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);
} 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(BTRFS_I(inode),
&ctx.ordered_extents);
ret = filemap_fdatawait_range(inode->i_mapping, start, end);
}
if (ret)
goto out_release_extents;
atomic_inc(&root->log_batch);
smp_mb();
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,
&BTRFS_I(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->i_mapping, file->f_wb_err);
goto out_release_extents;
}
/*
* 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);
btrfs_release_log_ctx_extents(&ctx);
if (ret < 0) {
/* Fallthrough and commit/free transaction. */
ret = 1;
}
/* 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.
*/
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
if (ret != BTRFS_NO_LOG_SYNC) {
if (!ret) {
ret = btrfs_sync_log(trans, root, &ctx);
if (!ret) {
ret = btrfs_end_transaction(trans);
goto out;
}
}
if (!full_sync) {
ret = btrfs_wait_ordered_range(inode, start, len);
if (ret) {
btrfs_end_transaction(trans);
goto out;
}
}
ret = btrfs_commit_transaction(trans);
} else {
ret = btrfs_end_transaction(trans);
}
out:
ASSERT(list_empty(&ctx.list));
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);
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
goto out;
}
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->readpage)
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 extent_map_tree *em_tree = &inode->extent_tree;
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_mark_buffer_dirty(leaf);
goto out;
}
if (hole_mergeable(inode, leaf, path->slots[0], offset, end)) {
u64 num_bytes;
key.offset = offset;
btrfs_set_item_key_safe(fs_info, 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_mark_buffer_dirty(leaf);
goto out;
}
btrfs_release_path(path);
ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode),
offset, 0, 0, end - offset, 0, end - offset, 0, 0, 0);
if (ret)
return ret;
out:
btrfs_release_path(path);
hole_em = alloc_extent_map();
if (!hole_em) {
btrfs_drop_extent_cache(inode, offset, end - 1, 0);
set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
} else {
hole_em->start = offset;
hole_em->len = end - offset;
hole_em->ram_bytes = hole_em->len;
hole_em->orig_start = offset;
hole_em->block_start = EXTENT_MAP_HOLE;
hole_em->block_len = 0;
hole_em->orig_block_len = 0;
hole_em->compress_type = BTRFS_COMPRESS_NONE;
hole_em->generation = trans->transid;
do {
btrfs_drop_extent_cache(inode, offset, end - 1, 0);
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, hole_em, 1);
write_unlock(&em_tree->lock);
} while (ret == -EEXIST);
free_extent_map(hole_em);
if (ret)
set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
&inode->runtime_flags);
}
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, 0,
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->block_start == 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 int btrfs_punch_hole_lock_range(struct inode *inode,
const u64 lockstart,
const u64 lockend,
struct extent_state **cached_state)
{
while (1) {
struct btrfs_ordered_extent *ordered;
int ret;
truncate_pagecache_range(inode, lockstart, lockend);
lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
cached_state);
ordered = btrfs_lookup_first_ordered_extent(BTRFS_I(inode),
lockend);
/*
* We need to make sure we have no ordered extents in this range
* and nobody raced in and read a page in this range, if we did
* we need to try again.
*/
if ((!ordered ||
(ordered->file_offset + ordered->num_bytes <= lockstart ||
ordered->file_offset > lockend)) &&
!filemap_range_has_page(inode->i_mapping,
lockstart, lockend)) {
if (ordered)
btrfs_put_ordered_extent(ordered);
break;
}
if (ordered)
btrfs_put_ordered_extent(ordered);
unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
lockend, cached_state);
ret = btrfs_wait_ordered_range(inode, lockstart,
lockend - lockstart + 1);
if (ret)
return ret;
}
return 0;
}
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;
struct btrfs_ref ref = { 0 };
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(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 {
u64 ref_offset;
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF,
extent_info->disk_offset,
extent_info->disk_len, 0);
ref_offset = extent_info->file_offset - extent_info->data_offset;
btrfs_init_data_ref(&ref, root->root_key.objectid,
btrfs_ino(inode), ref_offset);
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 = 1;
/*
* 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);
BUG_ON(ret);
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) {
/*
* When cloning we want to avoid transaction aborts when
* nothing was done and we are attempting to clone parts
* of inline extents, in such cases -EOPNOTSUPP is
* returned by __btrfs_drop_extents() without having
* changed anything in the file.
*/
if (extent_info && !extent_info->is_new_extent &&
ret && ret != -EOPNOTSUPP)
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;
}
ret = btrfs_update_inode(trans, root, 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);
BUG_ON(ret); /* shouldn't happen */
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)
set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &inode->runtime_flags);
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 inode *inode, loff_t offset, loff_t len)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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;
ret = btrfs_wait_ordered_range(inode, offset, len);
if (ret)
return ret;
btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
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;
}
lockstart = round_up(offset, btrfs_inode_sectorsize(BTRFS_I(inode)));
lockend = round_down(offset + len,
btrfs_inode_sectorsize(BTRFS_I(inode))) - 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(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;
}
ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
&cached_state);
if (ret)
goto out_only_mutex;
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->i_mtime = inode->i_ctime = current_time(inode);
ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
updated_inode = true;
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
out:
unlock_extent_cached(&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 = current_time(inode);
inode_inc_iversion(inode);
inode->i_mtime = now;
inode->i_ctime = now;
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
} else {
int ret2;
ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
ret2 = btrfs_end_transaction(trans);
if (!ret)
ret = ret2;
}
}
btrfs_inode_unlock(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 *prev = NULL;
struct falloc_range *range = NULL;
if (list_empty(head))
goto insert;
/*
* As fallocate iterate by bytenr order, we only need to check
* the last range.
*/
prev = list_entry(head->prev, struct falloc_range, list);
if (prev->start + prev->len == start) {
prev->len += len;
return 0;
}
insert:
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->i_ctime = current_time(inode);
i_size_write(inode, end);
btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
ret = btrfs_update_inode(trans, root, 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 = btrfs_inode_sectorsize(inode);
struct extent_map *em;
int ret;
offset = round_down(offset, sectorsize);
em = btrfs_get_extent(inode, NULL, 0, offset, sectorsize);
if (IS_ERR(em))
return PTR_ERR(em);
if (em->block_start == EXTENT_MAP_HOLE)
ret = RANGE_BOUNDARY_HOLE;
else if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
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 = btrfs_inode_sectorsize(BTRFS_I(inode));
u64 alloc_start = round_down(offset, sectorsize);
u64 alloc_end = round_up(offset + len, sectorsize);
u64 bytes_to_reserve = 0;
bool space_reserved = false;
inode_dio_wait(inode);
em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, 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 &&
test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
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 = em->block_start + 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, 0, alloc_start,
sectorsize);
if (IS_ERR(em)) {
ret = PTR_ERR(em);
goto out;
}
if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
free_extent_map(em);
ret = btrfs_fallocate_update_isize(inode, offset + len,
mode);
goto out;
}
if (len < sectorsize && em->block_start != 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;
ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
&cached_state);
if (ret)
goto out;
ret = btrfs_qgroup_reserve_data(BTRFS_I(inode), &data_reserved,
alloc_start, bytes_to_reserve);
if (ret) {
unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
lockend, &cached_state);
goto out;
}
ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
alloc_end - alloc_start,
i_blocksize(inode),
offset + len, &alloc_hint);
unlock_extent_cached(&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;
struct 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;
struct extent_map *em;
int blocksize = btrfs_inode_sectorsize(BTRFS_I(inode));
int ret;
/* Do not allow fallocate in ZONED mode */
if (btrfs_is_zoned(btrfs_sb(inode->i_sb)))
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(inode, offset, len);
/*
* Only trigger disk allocation, don't trigger qgroup reserve
*
* For qgroup space, it will be checked later.
*/
if (!(mode & FALLOC_FL_ZERO_RANGE)) {
ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
alloc_end - alloc_start);
if (ret < 0)
return ret;
}
btrfs_inode_lock(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;
}
/*
* 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;
}
/*
* wait for ordered IO before we have any locks. We'll loop again
* below with the locks held.
*/
ret = btrfs_wait_ordered_range(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(inode, BTRFS_ILOCK_MMAP);
return ret;
}
locked_end = alloc_end - 1;
while (1) {
struct btrfs_ordered_extent *ordered;
/* the extent lock is ordered inside the running
* transaction
*/
lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
locked_end, &cached_state);
ordered = btrfs_lookup_first_ordered_extent(BTRFS_I(inode),
locked_end);
if (ordered &&
ordered->file_offset + ordered->num_bytes > alloc_start &&
ordered->file_offset < alloc_end) {
btrfs_put_ordered_extent(ordered);
unlock_extent_cached(&BTRFS_I(inode)->io_tree,
alloc_start, locked_end,
&cached_state);
/*
* we can't wait on the range with the transaction
* running or with the extent lock held
*/
ret = btrfs_wait_ordered_range(inode, alloc_start,
alloc_end - alloc_start);
if (ret)
goto out;
} else {
if (ordered)
btrfs_put_ordered_extent(ordered);
break;
}
}
/* First, check if we exceed the qgroup limit */
INIT_LIST_HEAD(&reserve_list);
while (cur_offset < alloc_end) {
em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, 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->block_start == EXTENT_MAP_HOLE ||
(cur_offset >= inode->i_size &&
!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
ret = add_falloc_range(&reserve_list, cur_offset,
last_byte - cur_offset);
if (ret < 0) {
free_extent_map(em);
break;
}
ret = btrfs_qgroup_reserve_data(BTRFS_I(inode),
&data_reserved, cur_offset,
last_byte - cur_offset);
if (ret < 0) {
cur_offset = last_byte;
free_extent_map(em);
break;
}
} else {
/*
* Do not need to reserve unwritten extent for this
* range, free reserved data space first, otherwise
* it'll result in false ENOSPC error.
*/
btrfs_free_reserved_data_space(BTRFS_I(inode),
data_reserved, cur_offset,
last_byte - cur_offset);
}
free_extent_map(em);
cur_offset = last_byte;
}
/*
* 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, i_blocksize(inode),
offset + len, &alloc_hint);
else
btrfs_free_reserved_data_space(BTRFS_I(inode),
data_reserved, range->start,
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_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
&cached_state);
out:
btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
/* Let go of our reservation. */
if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
btrfs_free_reserved_data_space(BTRFS_I(inode), data_reserved,
cur_offset, alloc_end - cur_offset);
extent_changeset_free(data_reserved);
return ret;
}
static loff_t find_desired_extent(struct btrfs_inode *inode, loff_t offset,
int whence)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct extent_map *em = NULL;
struct extent_state *cached_state = NULL;
loff_t i_size = inode->vfs_inode.i_size;
u64 lockstart;
u64 lockend;
u64 start;
u64 len;
int ret = 0;
if (i_size == 0 || offset >= i_size)
return -ENXIO;
/*
* 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--;
len = lockend - lockstart + 1;
lock_extent_bits(&inode->io_tree, lockstart, lockend, &cached_state);
while (start < i_size) {
em = btrfs_get_extent_fiemap(inode, start, len);
if (IS_ERR(em)) {
ret = PTR_ERR(em);
em = NULL;
break;
}
if (whence == SEEK_HOLE &&
(em->block_start == EXTENT_MAP_HOLE ||
test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
break;
else if (whence == SEEK_DATA &&
(em->block_start != EXTENT_MAP_HOLE &&
!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
break;
start = em->start + em->len;
free_extent_map(em);
em = NULL;
cond_resched();
}
free_extent_map(em);
unlock_extent_cached(&inode->io_tree, lockstart, lockend,
&cached_state);
if (ret) {
offset = ret;
} else {
if (whence == SEEK_DATA && start >= i_size)
offset = -ENXIO;
else
offset = min_t(loff_t, start, i_size);
}
return offset;
}
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(inode, BTRFS_ILOCK_SHARED);
offset = find_desired_extent(BTRFS_I(inode), offset, whence);
btrfs_inode_unlock(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)
{
filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
return generic_file_open(inode, filp);
}
static int check_direct_read(struct btrfs_fs_info *fs_info,
const struct iov_iter *iter, loff_t offset)
{
int ret;
int i, seg;
ret = check_direct_IO(fs_info, iter, offset);
if (ret < 0)
return ret;
if (!iter_is_iovec(iter))
return 0;
for (seg = 0; seg < iter->nr_segs; seg++)
for (i = seg + 1; i < iter->nr_segs; i++)
if (iter->iov[seg].iov_base == iter->iov[i].iov_base)
return -EINVAL;
return 0;
}
static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to)
{
struct inode *inode = file_inode(iocb->ki_filp);
ssize_t ret;
if (check_direct_read(btrfs_sb(inode->i_sb), to, iocb->ki_pos))
return 0;
btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED);
ret = iomap_dio_rw(iocb, to, &btrfs_dio_iomap_ops, &btrfs_dio_ops, 0);
btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
return ret;
}
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 = generic_file_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,
.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,
};
void __cold btrfs_auto_defrag_exit(void)
{
kmem_cache_destroy(btrfs_inode_defrag_cachep);
}
int __init btrfs_auto_defrag_init(void)
{
btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
sizeof(struct inode_defrag), 0,
SLAB_MEM_SPREAD,
NULL);
if (!btrfs_inode_defrag_cachep)
return -ENOMEM;
return 0;
}
int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end)
{
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(inode->i_mapping, start, end);
if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
&BTRFS_I(inode)->runtime_flags))
ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
return ret;
}
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