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authorChris Mason <chris.mason@oracle.com>2008-11-07 12:35:44 -0500
committerChris Mason <chris.mason@oracle.com>2008-11-07 12:35:44 -0500
commitaf09abfece59aa50bfbf16f6f1f85822554e061f (patch)
treeca419511219b433a2bf45626814777df8667a19f /fs/btrfs/compression.c
parent4366211ccd050e00674b3276b5ed81981b2d7793 (diff)
downloadblackbird-op-linux-af09abfece59aa50bfbf16f6f1f85822554e061f.tar.gz
blackbird-op-linux-af09abfece59aa50bfbf16f6f1f85822554e061f.zip
Btrfs: make sure compressed bios don't complete too soon
When writing a compressed extent, a number of bios are created that point to a single struct compressed_bio. At end_io time an atomic counter in the compressed_bio struct makes sure that all of the bios have finished before final end_io processing is done. But when multiple bios are needed to write a compressed extent, the counter was being incremented after the first bio was sent to submit_bio. It is possible the bio will complete before the counter is incremented, making the end_io handler free the compressed_bio struct before processing is finished. The fix is to increment the atomic counter before bio submission, both for compressed reads and writes. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/compression.c')
-rw-r--r--fs/btrfs/compression.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 284f21025bcc..7397c622fb6a 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -314,6 +314,13 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
PAGE_CACHE_SIZE) {
bio_get(bio);
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
BUG_ON(ret);
@@ -323,7 +330,6 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
bio_put(bio);
bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
- atomic_inc(&cb->pending_bios);
bio->bi_private = cb;
bio->bi_end_io = end_compressed_bio_write;
bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
@@ -573,6 +579,14 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
ret = btrfs_bio_wq_end_io(root->fs_info, comp_bio, 0);
BUG_ON(ret);
+ /*
+ * inc the count before we submit the bio so
+ * we know the end IO handler won't happen before
+ * we inc the count. Otherwise, the cb might get
+ * freed before we're done setting it up
+ */
+ atomic_inc(&cb->pending_bios);
+
ret = btrfs_map_bio(root, READ, comp_bio, 0, 0);
BUG_ON(ret);
@@ -580,7 +594,6 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
GFP_NOFS);
- atomic_inc(&cb->pending_bios);
comp_bio->bi_private = cb;
comp_bio->bi_end_io = end_compressed_bio_read;
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