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[dm-devel] [PATCH 1/2 block#for-2.6.36] bio, fs: update RWA_MASK, READA and SWRITE to match the corresponding BIO_RW_* bits



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 RW_MASK, RWA_MASK, 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 RWA_MASK, READA and SWRITE.

This patch updates RWA_MASK, 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.

Neil also spotted missing RWA_MASK conversion.

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
---
Here's the regenerated version also w/ the missing RWA_MASK conversion
Neil spotted.

Thanks.

 include/linux/fs.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: work/include/linux/fs.h
===================================================================
--- work.orig/include/linux/fs.h
+++ work/include/linux/fs.h
@@ -145,12 +145,12 @@ struct inodes_stat_t {
  *
  */
 #define RW_MASK			1
-#define RWA_MASK		2
+#define RWA_MASK		16

 #define READ			0
 #define WRITE			1
-#define READA			2 /* readahead  - don't block if no resources */
-#define SWRITE			3 /* for ll_rw_block() - wait for buffer lock */
+#define READA			16 /* readahead - don't block if no resources */
+#define SWRITE			17 /* for ll_rw_block(), wait for buffer lock */

 #define READ_SYNC		(READ | REQ_SYNC | REQ_UNPLUG)
 #define READ_META		(READ | REQ_META)


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