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authorLiu Bo <bo.li.liu@oracle.com>2016-07-11 10:39:07 -0700
committerDavid Sterba <dsterba@suse.com>2016-07-26 13:52:25 +0200
commitbaf863b9c29617cc9eaf24e039f58846e700db48 (patch)
tree916fe6a7c3967160de5d6d991dd6e1088953add8 /fs/btrfs
parentf49070957ffed84feb7944550f7edd53672b5201 (diff)
Btrfs: fix eb memory leak due to readpage failure
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>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/extent_io.c25
1 files changed, 22 insertions, 3 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ea12d0ee684f..dae2f8470e04 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -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);
}