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fs: introduce write_begin, write_end, and perform_write aops

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These are intended to replace prepare_write and commit_write with more
flexible alternatives that are also able to avoid the buffered write
deadlock problems efficiently (which prepare_write is unable to do).

[mark.fasheh@oracle.com: API design contributions, code review and fixes]
[akpm@linux-foundation.org: various fixes]
[dmonakhov@sw.ru: new aop block_write_begin fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2007-10-16 01:25:01 -07:00 • committed by Linus Torvalds
parent 637aff46f9
commit afddba49d1
11 changed files with 575 additions and 206 deletions
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69
fs/splice.c
View file

@ -563,7 +563,7 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
struct address_space *mapping = file->f_mapping;
unsigned int offset, this_len;
struct page *page;
pgoff_t index;
void *fsdata;
int ret;
/*
@ -573,49 +573,16 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
if (unlikely(ret))
return ret;
index = sd->pos >> PAGE_CACHE_SHIFT;
offset = sd->pos & ~PAGE_CACHE_MASK;
this_len = sd->len;
if (this_len + offset > PAGE_CACHE_SIZE)
this_len = PAGE_CACHE_SIZE - offset;
find_page:
page = find_lock_page(mapping, index);
if (!page) {
ret = -ENOMEM;
page = page_cache_alloc_cold(mapping);
if (unlikely(!page))
goto out_ret;
/*
* This will also lock the page
*/
ret = add_to_page_cache_lru(page, mapping, index,
GFP_KERNEL);
if (unlikely(ret))
goto out_release;
}
ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
if (unlikely(ret)) {
loff_t isize = i_size_read(mapping->host);
if (ret != AOP_TRUNCATED_PAGE)
unlock_page(page);
page_cache_release(page);
if (ret == AOP_TRUNCATED_PAGE)
goto find_page;
/*
* prepare_write() may have instantiated a few blocks
* outside i_size. Trim these off again.
*/
if (sd->pos + this_len > isize)
vmtruncate(mapping->host, isize);
goto out_ret;
}
ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
if (unlikely(ret))
goto out;
if (buf->page != page) {
/*
@ -629,31 +596,9 @@ find_page:
kunmap_atomic(dst, KM_USER1);
buf->ops->unmap(pipe, buf, src);
}
ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
if (ret) {
if (ret == AOP_TRUNCATED_PAGE) {
page_cache_release(page);
goto find_page;
}
if (ret < 0)
goto out;
/*
* Partial write has happened, so 'ret' already initialized by
* number of bytes written, Where is nothing we have to do here.
*/
} else
ret = this_len;
/*
* Return the number of bytes written and mark page as
* accessed, we are now done!
*/
mark_page_accessed(page);
ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
page, fsdata);
out:
unlock_page(page);
out_release:
page_cache_release(page);
out_ret:
return ret;
}