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Btrfs: fix eb memory leak due to readpage failure

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eb->io_pages is set in read_extent_buffer_pages().

In case of readpage failure, for pages that have been added to bio,
it calls bio_endio and later readpage_io_failed_hook() does the work.

When this eb's page (couldn't be the 1st page) fails to add itself to bio
due to failure in merge_bio(), it cannot decrease eb->io_pages via bio_endio,
 and ends up with a memory leak eventually.

This lets __do_readpage propagate errors to callers and adds the
 'atomic_dec(&eb->io_pages)'.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2016-07-11 10:39:07 -07:00 committed by David Sterba
parent f49070957f
commit baf863b9c2
1 changed files with 22 additions and 3 deletions
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25
fs/btrfs/extent_io.c
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@ -2878,6 +2878,7 @@ __get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
* into the tree that are removed when the IO is done (by the end_io
* handlers)
* XXX JDM: This needs looking at to ensure proper page locking
* return 0 on success, otherwise return error
*/
static int __do_readpage(struct extent_io_tree *tree,
struct page *page,
@ -2899,7 +2900,7 @@ static int __do_readpage(struct extent_io_tree *tree,
sector_t sector;
struct extent_map *em;
struct block_device *bdev;
int ret;
int ret = 0;
int nr = 0;
size_t pg_offset = 0;
size_t iosize;
@ -3080,6 +3081,7 @@ static int __do_readpage(struct extent_io_tree *tree,
} else {
SetPageError(page);
unlock_extent(tree, cur, cur + iosize - 1);
goto out;
}
cur = cur + iosize;
pg_offset += iosize;
@ -3090,7 +3092,7 @@ out:
SetPageUptodate(page);
unlock_page(page);
}
return 0;
return ret;
}
static inline void __do_contiguous_readpages(struct extent_io_tree *tree,
@ -5230,14 +5232,31 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
atomic_set(&eb->io_pages, num_reads);
for (i = start_i; i < num_pages; i++) {
page = eb->pages[i];
if (!PageUptodate(page)) {
if (ret) {
atomic_dec(&eb->io_pages);
unlock_page(page);
continue;
}
ClearPageError(page);
err = __extent_read_full_page(tree, page,
get_extent, &bio,
mirror_num, &bio_flags,
READ | REQ_META);
if (err)
if (err) {
ret = err;
/*
* We use &bio in above __extent_read_full_page,
* so we ensure that if it returns error, the
* current page fails to add itself to bio and
* it's been unlocked.
*
* We must dec io_pages by ourselves.
*/
atomic_dec(&eb->io_pages);
}
} else {
unlock_page(page);
}