Messages in this thread Patch in this message | | | Date | Mon, 02 Aug 2010 16:17:59 +0200 | From | Tejun Heo <> | Subject | [PATCH RESEND 1/2 block#for-linus] bio, fs: update READA and SWRITE to match the corresponding BIO_RW_* bits |
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Commit a82afdf (block: use the same failfast bits for bio and request) moved BIO_RW_* bits around such that they match up with REQ_* bits. Unfortunately, fs.h hard coded READ, WRITE, READA and SWRITE as 0, 1, 2 and 3, and expected them to match with BIO_RW_* bits. READ/WRITE didn't change but BIO_RW_AHEAD was moved to bit 4 instead of bit 1, breaking READA and SWRITE.
This patch updates READA and SWRITE such that they match the BIO_RW_* bits again. A follow up patch will update the definitions to directly use BIO_RW_* bits so that this kind of breakage won't happen again.
Stable: The offending commit a82afdf was released with v2.6.32, so this patch should be applied to all kernels since then but it must _NOT_ be applied to kernels earlier than that.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-bisected-by: Vladislav Bolkhovitin <vst@vlnb.net> Root-caused-by: Neil Brown <neilb@suse.de> Cc: Jens Axobe <axboe@kernel.dk> Cc: stable@kernel.org --- Aieee... thanks for root causing it Neil. That was a stupid bug. I knew that READ/WRITE were hardcoded but forgot about READA. :-( Moving BIO_RW_AHEAD back to bit 1 might be a better solution but I'm afraid that would cause more confusions downstream. This patch updates READA and SWRITE to match BIO_RW_AHEAD and should also appear in -stable releases. The next patch will create bio_types.h and define all constants in terms of BIO_RW_*.
Thanks.
(resending w/ Jens' new address)
include/linux/fs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Index: work/include/linux/fs.h =================================================================== --- work.orig/include/linux/fs.h +++ work/include/linux/fs.h @@ -148,8 +148,8 @@ struct inodes_stat_t { #define RWA_MASK 2 #define READ 0 #define WRITE 1 -#define READA 2 /* read-ahead - don't block if no resources */ -#define SWRITE 3 /* for ll_rw_block() - wait for buffer lock */ +#define READA 16 /* read-ahead - don't block if no resources */ +#define SWRITE 17 /* for ll_rw_block() - wait for buffer lock */ #define READ_SYNC (READ | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG)) #define READ_META (READ | (1 << BIO_RW_META)) #define WRITE_SYNC_PLUG (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))
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