mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-13 05:54:23 +08:00
587 lines
14 KiB
C
587 lines
14 KiB
C
/*
|
|
* Copyright (C) 2010 Red Hat, Inc.
|
|
* Copyright (c) 2016 Christoph Hellwig.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms and conditions of the GNU General Public License,
|
|
* version 2, as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
|
|
* more details.
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/iomap.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/file.h>
|
|
#include <linux/uio.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/buffer_head.h>
|
|
#include <linux/dax.h>
|
|
#include "internal.h"
|
|
|
|
/*
|
|
* Execute a iomap write on a segment of the mapping that spans a
|
|
* contiguous range of pages that have identical block mapping state.
|
|
*
|
|
* This avoids the need to map pages individually, do individual allocations
|
|
* for each page and most importantly avoid the need for filesystem specific
|
|
* locking per page. Instead, all the operations are amortised over the entire
|
|
* range of pages. It is assumed that the filesystems will lock whatever
|
|
* resources they require in the iomap_begin call, and release them in the
|
|
* iomap_end call.
|
|
*/
|
|
loff_t
|
|
iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
|
|
struct iomap_ops *ops, void *data, iomap_actor_t actor)
|
|
{
|
|
struct iomap iomap = { 0 };
|
|
loff_t written = 0, ret;
|
|
|
|
/*
|
|
* Need to map a range from start position for length bytes. This can
|
|
* span multiple pages - it is only guaranteed to return a range of a
|
|
* single type of pages (e.g. all into a hole, all mapped or all
|
|
* unwritten). Failure at this point has nothing to undo.
|
|
*
|
|
* If allocation is required for this range, reserve the space now so
|
|
* that the allocation is guaranteed to succeed later on. Once we copy
|
|
* the data into the page cache pages, then we cannot fail otherwise we
|
|
* expose transient stale data. If the reserve fails, we can safely
|
|
* back out at this point as there is nothing to undo.
|
|
*/
|
|
ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
|
|
if (ret)
|
|
return ret;
|
|
if (WARN_ON(iomap.offset > pos))
|
|
return -EIO;
|
|
|
|
/*
|
|
* Cut down the length to the one actually provided by the filesystem,
|
|
* as it might not be able to give us the whole size that we requested.
|
|
*/
|
|
if (iomap.offset + iomap.length < pos + length)
|
|
length = iomap.offset + iomap.length - pos;
|
|
|
|
/*
|
|
* Now that we have guaranteed that the space allocation will succeed.
|
|
* we can do the copy-in page by page without having to worry about
|
|
* failures exposing transient data.
|
|
*/
|
|
written = actor(inode, pos, length, data, &iomap);
|
|
|
|
/*
|
|
* Now the data has been copied, commit the range we've copied. This
|
|
* should not fail unless the filesystem has had a fatal error.
|
|
*/
|
|
if (ops->iomap_end) {
|
|
ret = ops->iomap_end(inode, pos, length,
|
|
written > 0 ? written : 0,
|
|
flags, &iomap);
|
|
}
|
|
|
|
return written ? written : ret;
|
|
}
|
|
|
|
static void
|
|
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
|
|
{
|
|
loff_t i_size = i_size_read(inode);
|
|
|
|
/*
|
|
* Only truncate newly allocated pages beyoned EOF, even if the
|
|
* write started inside the existing inode size.
|
|
*/
|
|
if (pos + len > i_size)
|
|
truncate_pagecache_range(inode, max(pos, i_size), pos + len);
|
|
}
|
|
|
|
static int
|
|
iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
|
|
struct page **pagep, struct iomap *iomap)
|
|
{
|
|
pgoff_t index = pos >> PAGE_SHIFT;
|
|
struct page *page;
|
|
int status = 0;
|
|
|
|
BUG_ON(pos + len > iomap->offset + iomap->length);
|
|
|
|
page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
status = __block_write_begin_int(page, pos, len, NULL, iomap);
|
|
if (unlikely(status)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page = NULL;
|
|
|
|
iomap_write_failed(inode, pos, len);
|
|
}
|
|
|
|
*pagep = page;
|
|
return status;
|
|
}
|
|
|
|
static int
|
|
iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
|
|
unsigned copied, struct page *page)
|
|
{
|
|
int ret;
|
|
|
|
ret = generic_write_end(NULL, inode->i_mapping, pos, len,
|
|
copied, page, NULL);
|
|
if (ret < len)
|
|
iomap_write_failed(inode, pos, len);
|
|
return ret;
|
|
}
|
|
|
|
static loff_t
|
|
iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap)
|
|
{
|
|
struct iov_iter *i = data;
|
|
long status = 0;
|
|
ssize_t written = 0;
|
|
unsigned int flags = AOP_FLAG_NOFS;
|
|
|
|
/*
|
|
* Copies from kernel address space cannot fail (NFSD is a big user).
|
|
*/
|
|
if (!iter_is_iovec(i))
|
|
flags |= AOP_FLAG_UNINTERRUPTIBLE;
|
|
|
|
do {
|
|
struct page *page;
|
|
unsigned long offset; /* Offset into pagecache page */
|
|
unsigned long bytes; /* Bytes to write to page */
|
|
size_t copied; /* Bytes copied from user */
|
|
|
|
offset = (pos & (PAGE_SIZE - 1));
|
|
bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
|
iov_iter_count(i));
|
|
again:
|
|
if (bytes > length)
|
|
bytes = length;
|
|
|
|
/*
|
|
* Bring in the user page that we will copy from _first_.
|
|
* Otherwise there's a nasty deadlock on copying from the
|
|
* same page as we're writing to, without it being marked
|
|
* up-to-date.
|
|
*
|
|
* Not only is this an optimisation, but it is also required
|
|
* to check that the address is actually valid, when atomic
|
|
* usercopies are used, below.
|
|
*/
|
|
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
|
status = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
status = iomap_write_begin(inode, pos, bytes, flags, &page,
|
|
iomap);
|
|
if (unlikely(status))
|
|
break;
|
|
|
|
if (mapping_writably_mapped(inode->i_mapping))
|
|
flush_dcache_page(page);
|
|
|
|
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
|
|
|
flush_dcache_page(page);
|
|
|
|
status = iomap_write_end(inode, pos, bytes, copied, page);
|
|
if (unlikely(status < 0))
|
|
break;
|
|
copied = status;
|
|
|
|
cond_resched();
|
|
|
|
iov_iter_advance(i, copied);
|
|
if (unlikely(copied == 0)) {
|
|
/*
|
|
* If we were unable to copy any data at all, we must
|
|
* fall back to a single segment length write.
|
|
*
|
|
* If we didn't fallback here, we could livelock
|
|
* because not all segments in the iov can be copied at
|
|
* once without a pagefault.
|
|
*/
|
|
bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
|
iov_iter_single_seg_count(i));
|
|
goto again;
|
|
}
|
|
pos += copied;
|
|
written += copied;
|
|
length -= copied;
|
|
|
|
balance_dirty_pages_ratelimited(inode->i_mapping);
|
|
} while (iov_iter_count(i) && length);
|
|
|
|
return written ? written : status;
|
|
}
|
|
|
|
ssize_t
|
|
iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
|
|
struct iomap_ops *ops)
|
|
{
|
|
struct inode *inode = iocb->ki_filp->f_mapping->host;
|
|
loff_t pos = iocb->ki_pos, ret = 0, written = 0;
|
|
|
|
while (iov_iter_count(iter)) {
|
|
ret = iomap_apply(inode, pos, iov_iter_count(iter),
|
|
IOMAP_WRITE, ops, iter, iomap_write_actor);
|
|
if (ret <= 0)
|
|
break;
|
|
pos += ret;
|
|
written += ret;
|
|
}
|
|
|
|
return written ? written : ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
|
|
|
|
static struct page *
|
|
__iomap_read_page(struct inode *inode, loff_t offset)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct page *page;
|
|
|
|
page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
|
|
if (IS_ERR(page))
|
|
return page;
|
|
if (!PageUptodate(page)) {
|
|
put_page(page);
|
|
return ERR_PTR(-EIO);
|
|
}
|
|
return page;
|
|
}
|
|
|
|
static loff_t
|
|
iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap)
|
|
{
|
|
long status = 0;
|
|
ssize_t written = 0;
|
|
|
|
do {
|
|
struct page *page, *rpage;
|
|
unsigned long offset; /* Offset into pagecache page */
|
|
unsigned long bytes; /* Bytes to write to page */
|
|
|
|
offset = (pos & (PAGE_SIZE - 1));
|
|
bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
|
|
|
|
rpage = __iomap_read_page(inode, pos);
|
|
if (IS_ERR(rpage))
|
|
return PTR_ERR(rpage);
|
|
|
|
status = iomap_write_begin(inode, pos, bytes,
|
|
AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE,
|
|
&page, iomap);
|
|
put_page(rpage);
|
|
if (unlikely(status))
|
|
return status;
|
|
|
|
WARN_ON_ONCE(!PageUptodate(page));
|
|
|
|
status = iomap_write_end(inode, pos, bytes, bytes, page);
|
|
if (unlikely(status <= 0)) {
|
|
if (WARN_ON_ONCE(status == 0))
|
|
return -EIO;
|
|
return status;
|
|
}
|
|
|
|
cond_resched();
|
|
|
|
pos += status;
|
|
written += status;
|
|
length -= status;
|
|
|
|
balance_dirty_pages_ratelimited(inode->i_mapping);
|
|
} while (length);
|
|
|
|
return written;
|
|
}
|
|
|
|
int
|
|
iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
|
|
struct iomap_ops *ops)
|
|
{
|
|
loff_t ret;
|
|
|
|
while (len) {
|
|
ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
|
|
iomap_dirty_actor);
|
|
if (ret <= 0)
|
|
return ret;
|
|
pos += ret;
|
|
len -= ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_file_dirty);
|
|
|
|
static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
|
|
unsigned bytes, struct iomap *iomap)
|
|
{
|
|
struct page *page;
|
|
int status;
|
|
|
|
status = iomap_write_begin(inode, pos, bytes,
|
|
AOP_FLAG_UNINTERRUPTIBLE | AOP_FLAG_NOFS, &page, iomap);
|
|
if (status)
|
|
return status;
|
|
|
|
zero_user(page, offset, bytes);
|
|
mark_page_accessed(page);
|
|
|
|
return iomap_write_end(inode, pos, bytes, bytes, page);
|
|
}
|
|
|
|
static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
|
|
struct iomap *iomap)
|
|
{
|
|
sector_t sector = iomap->blkno +
|
|
(((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
|
|
|
|
return __dax_zero_page_range(iomap->bdev, sector, offset, bytes);
|
|
}
|
|
|
|
static loff_t
|
|
iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
|
|
void *data, struct iomap *iomap)
|
|
{
|
|
bool *did_zero = data;
|
|
loff_t written = 0;
|
|
int status;
|
|
|
|
/* already zeroed? we're done. */
|
|
if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
|
|
return count;
|
|
|
|
do {
|
|
unsigned offset, bytes;
|
|
|
|
offset = pos & (PAGE_SIZE - 1); /* Within page */
|
|
bytes = min_t(unsigned, PAGE_SIZE - offset, count);
|
|
|
|
if (IS_DAX(inode))
|
|
status = iomap_dax_zero(pos, offset, bytes, iomap);
|
|
else
|
|
status = iomap_zero(inode, pos, offset, bytes, iomap);
|
|
if (status < 0)
|
|
return status;
|
|
|
|
pos += bytes;
|
|
count -= bytes;
|
|
written += bytes;
|
|
if (did_zero)
|
|
*did_zero = true;
|
|
} while (count > 0);
|
|
|
|
return written;
|
|
}
|
|
|
|
int
|
|
iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
|
|
struct iomap_ops *ops)
|
|
{
|
|
loff_t ret;
|
|
|
|
while (len > 0) {
|
|
ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
|
|
ops, did_zero, iomap_zero_range_actor);
|
|
if (ret <= 0)
|
|
return ret;
|
|
|
|
pos += ret;
|
|
len -= ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_zero_range);
|
|
|
|
int
|
|
iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
|
|
struct iomap_ops *ops)
|
|
{
|
|
unsigned blocksize = (1 << inode->i_blkbits);
|
|
unsigned off = pos & (blocksize - 1);
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!off)
|
|
return 0;
|
|
return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_truncate_page);
|
|
|
|
static loff_t
|
|
iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
|
|
void *data, struct iomap *iomap)
|
|
{
|
|
struct page *page = data;
|
|
int ret;
|
|
|
|
ret = __block_write_begin_int(page, pos & ~PAGE_MASK, length,
|
|
NULL, iomap);
|
|
if (ret)
|
|
return ret;
|
|
|
|
block_commit_write(page, 0, length);
|
|
return length;
|
|
}
|
|
|
|
int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
struct iomap_ops *ops)
|
|
{
|
|
struct page *page = vmf->page;
|
|
struct inode *inode = file_inode(vma->vm_file);
|
|
unsigned long length;
|
|
loff_t offset, size;
|
|
ssize_t ret;
|
|
|
|
lock_page(page);
|
|
size = i_size_read(inode);
|
|
if ((page->mapping != inode->i_mapping) ||
|
|
(page_offset(page) > size)) {
|
|
/* We overload EFAULT to mean page got truncated */
|
|
ret = -EFAULT;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* page is wholly or partially inside EOF */
|
|
if (((page->index + 1) << PAGE_SHIFT) > size)
|
|
length = size & ~PAGE_MASK;
|
|
else
|
|
length = PAGE_SIZE;
|
|
|
|
offset = page_offset(page);
|
|
while (length > 0) {
|
|
ret = iomap_apply(inode, offset, length, IOMAP_WRITE,
|
|
ops, page, iomap_page_mkwrite_actor);
|
|
if (unlikely(ret <= 0))
|
|
goto out_unlock;
|
|
offset += ret;
|
|
length -= ret;
|
|
}
|
|
|
|
set_page_dirty(page);
|
|
wait_for_stable_page(page);
|
|
return 0;
|
|
out_unlock:
|
|
unlock_page(page);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
|
|
|
|
struct fiemap_ctx {
|
|
struct fiemap_extent_info *fi;
|
|
struct iomap prev;
|
|
};
|
|
|
|
static int iomap_to_fiemap(struct fiemap_extent_info *fi,
|
|
struct iomap *iomap, u32 flags)
|
|
{
|
|
switch (iomap->type) {
|
|
case IOMAP_HOLE:
|
|
/* skip holes */
|
|
return 0;
|
|
case IOMAP_DELALLOC:
|
|
flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
flags |= FIEMAP_EXTENT_UNWRITTEN;
|
|
break;
|
|
case IOMAP_MAPPED:
|
|
break;
|
|
}
|
|
|
|
if (iomap->flags & IOMAP_F_MERGED)
|
|
flags |= FIEMAP_EXTENT_MERGED;
|
|
if (iomap->flags & IOMAP_F_SHARED)
|
|
flags |= FIEMAP_EXTENT_SHARED;
|
|
|
|
return fiemap_fill_next_extent(fi, iomap->offset,
|
|
iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
|
|
iomap->length, flags);
|
|
|
|
}
|
|
|
|
static loff_t
|
|
iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap)
|
|
{
|
|
struct fiemap_ctx *ctx = data;
|
|
loff_t ret = length;
|
|
|
|
if (iomap->type == IOMAP_HOLE)
|
|
return length;
|
|
|
|
ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0);
|
|
ctx->prev = *iomap;
|
|
switch (ret) {
|
|
case 0: /* success */
|
|
return length;
|
|
case 1: /* extent array full */
|
|
return 0;
|
|
default:
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
|
|
loff_t start, loff_t len, struct iomap_ops *ops)
|
|
{
|
|
struct fiemap_ctx ctx;
|
|
loff_t ret;
|
|
|
|
memset(&ctx, 0, sizeof(ctx));
|
|
ctx.fi = fi;
|
|
ctx.prev.type = IOMAP_HOLE;
|
|
|
|
ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
|
|
ret = filemap_write_and_wait(inode->i_mapping);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
while (len > 0) {
|
|
ret = iomap_apply(inode, start, len, 0, ops, &ctx,
|
|
iomap_fiemap_actor);
|
|
/* inode with no (attribute) mapping will give ENOENT */
|
|
if (ret == -ENOENT)
|
|
break;
|
|
if (ret < 0)
|
|
return ret;
|
|
if (ret == 0)
|
|
break;
|
|
|
|
start += ret;
|
|
len -= ret;
|
|
}
|
|
|
|
if (ctx.prev.type != IOMAP_HOLE) {
|
|
ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST);
|
|
if (ret < 0)
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_fiemap);
|