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nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection

PATCH In review Vyacheslav Dubeyko 2 participants 2 messages Aug 13, 2013 – Aug 14, 2013

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Vyacheslav Dubeyko

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#0 lore raw

PATCH v3 2/2 nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection

From: Vyacheslav Dubeyko <[email protected]>
Subject: [PATCH v3 2/2] nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection

This patch fixes the issue with improper counting number of flying bio requests for BIO_EOPNOTSUPP error detection case.

The sb_nbio must be incremented exactly the same number of times as complete() function was called (or will be called) because nilfs_segbuf_wait() will call wail_for_completion() for the number of times set to sb_nbio:

do {
    wait_for_completion(&segbuf->sb_bio_event);
} while (--segbuf->sb_nbio > 0);

Two functions complete() and wait_for_completion() must be called the same number of times for the same sb_bio_event. Otherwise, wait_for_completion() will hang or leak.

Signed-off-by Vyacheslav Dubeyko <[email protected]>
CC Ryusuke Konishi <[email protected]>
CC Dan Carpenter <[email protected]>
---
 fs/nilfs2/segbuf.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
fs/nilfs2/segbuf.c +1 -1
index 5bacf46..2d8be51 100644
@@ -376,12 +376,12 @@ static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 	bio->bi_private = segbuf;
 	bio_get(bio);
 	submit_bio(mode, bio);
+	segbuf->sb_nbio++;
 	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 		bio_put(bio);
 		err = -EOPNOTSUPP;
 		goto failed;
 	}
-	segbuf->sb_nbio++;
 	bio_put(bio);
 
 	wi->bio = NULL;
Signature · 1 line
1.7.9.5
Acked-by Tested-by on v3 2/2
#1 lore raw
Quoted 15 lines · Vyacheslav Dubeyko

From: Vyacheslav Dubeyko <[email protected]>
Subject: [PATCH v3 2/2] nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection

This patch fixes the issue with improper counting number of flying bio requests for BIO_EOPNOTSUPP error detection case.

The sb_nbio must be incremented exactly the same number of times as complete() function was called (or will be called) because nilfs_segbuf_wait() will call wail_for_completion() for the number of times set to sb_nbio:

do {
    wait_for_completion(&segbuf->sb_bio_event);
} while (--segbuf->sb_nbio > 0);
Quoted 6 lines

Two functions complete() and wait_for_completion() must be called the same number of times for the same sb_bio_event. Otherwise, wait_for_completion() will hang or leak.

Signed-off-by Vyacheslav Dubeyko <[email protected]>
CC Ryusuke Konishi <[email protected]>
Acked-by Ryusuke Konishi <[email protected]>
Tested-by Ryusuke Konishi <[email protected]>

I confirmed that this fixes the leak of wait_for_completion() for the BIO_EOPNOTSUPP error detection case.

Andrew, please send this upstream along with the companion patch titled "nilfs2: remove double bio_put() in nilfs_end_bio_write() for BIO_EOPNOTSUPP error".

Thanks,
Ryusuke Konishi

Quoted 32 lines
CC Dan Carpenter <[email protected]>
---
 fs/nilfs2/segbuf.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
fs/nilfs2/segbuf.c +1 -1
index 5bacf46..2d8be51 100644
@@ -376,12 +376,12 @@ static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 	bio->bi_private = segbuf;
 	bio_get(bio);
 	submit_bio(mode, bio);
+	segbuf->sb_nbio++;
 	if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 		bio_put(bio);
 		err = -EOPNOTSUPP;
 		goto failed;
 	}
-	segbuf->sb_nbio++;
 	bio_put(bio);
 
 	wi->bio = NULL;
Signature · 8 lines
1.7.9.5



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