On Thu, Sep 13, 2007 at 11:30:37AM -0500, Benjamin Marzinski wrote:
> gfs2 was deadlocking because most code paths acquire the sd_log_flush_lock and
> then the page locks, while code paths going through gfs2_writepage acquire the
> page locks and then the log flush lock.
>
> This patch makes gfs2_writepage do a trylock on the sd_log_flush_lock. If it
> fails, writepage simply redirtys the page and gives up. This should keep the
> deadlock from happening, however it might cause a performance hit.
>
> Signed-off-by: Benjamin E. Marzinski <[EMAIL PROTECTED]>
And here is the actual patch
diff -urpN
--exclude-from=linux-2.6.18-44.gfs2abhi.003_test_clean/Documentation/dontdiff
linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/log.c
linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/log.c
--- linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/log.c 2007-09-05
09:33:11.000000000 -0500
+++ linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/log.c 2007-09-11
10:03:48.000000000 -0500
@@ -288,7 +288,7 @@ static void ail2_empty(struct gfs2_sbd *
* Returns: errno
*/
-int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
+int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks, int wait)
{
unsigned int try = 0;
unsigned reserved_blks = 6 * (4096 / sdp->sd_vfs->s_blocksize);
@@ -301,6 +301,10 @@ int gfs2_log_reserve(struct gfs2_sbd *sd
gfs2_log_lock(sdp);
while(sdp->sd_log_blks_free <= (blks + reserved_blks)) {
gfs2_log_unlock(sdp);
+ if (!wait) {
+ mutex_unlock(&sdp->sd_log_reserve_mutex);
+ return -EBUSY;
+ }
gfs2_ail1_empty(sdp, 0);
gfs2_log_flush(sdp, NULL);
@@ -310,10 +314,21 @@ int gfs2_log_reserve(struct gfs2_sbd *sd
}
sdp->sd_log_blks_free -= blks;
gfs2_log_unlock(sdp);
- mutex_unlock(&sdp->sd_log_reserve_mutex);
-
- down_read(&sdp->sd_log_flush_lock);
+ if (wait){
+ mutex_unlock(&sdp->sd_log_reserve_mutex);
+ down_read(&sdp->sd_log_flush_lock);
+ }
+ else {
+ if (!down_read_trylock(&sdp->sd_log_flush_lock)) {
+ gfs2_log_lock(sdp);
+ sdp->sd_log_blks_free += blks;
+ gfs2_log_unlock(sdp);
+ mutex_unlock(&sdp->sd_log_reserve_mutex);
+ return -EBUSY;
+ }
+ mutex_unlock(&sdp->sd_log_reserve_mutex);
+ }
return 0;
}
diff -urpN
--exclude-from=linux-2.6.18-44.gfs2abhi.003_test_clean/Documentation/dontdiff
linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/log.h
linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/log.h
--- linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/log.h 2007-08-29
14:11:37.000000000 -0500
+++ linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/log.h 2007-09-09
08:18:08.000000000 -0500
@@ -50,7 +50,7 @@ unsigned int gfs2_struct2blk(struct gfs2
int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags);
-int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks);
+int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks, int wait);
void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks);
struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp);
diff -urpN
--exclude-from=linux-2.6.18-44.gfs2abhi.003_test_clean/Documentation/dontdiff
linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/ops_address.c
linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/ops_address.c
--- linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/ops_address.c
2007-08-29 14:11:37.000000000 -0500
+++ linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/ops_address.c 2007-09-09
08:20:50.000000000 -0500
@@ -140,7 +140,7 @@ static int gfs2_writepage(struct page *p
if ((sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) &&
PageChecked(page)) {
ClearPageChecked(page);
- error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
+ error = gfs2_do_trans_begin(sdp, RES_DINODE + 1, 0, 0);
if (error)
goto out_ignore;
if (!page_has_buffers(page)) {
diff -urpN
--exclude-from=linux-2.6.18-44.gfs2abhi.003_test_clean/Documentation/dontdiff
linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/trans.c
linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/trans.c
--- linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/trans.c 2007-09-04
07:45:25.000000000 -0500
+++ linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/trans.c 2007-09-09
09:23:05.000000000 -0500
@@ -25,8 +25,8 @@
#include "trans.h"
#include "util.h"
-int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
- unsigned int revokes)
+int gfs2_do_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
+ unsigned int revokes, int wait)
{
struct gfs2_trans *tr;
int error;
@@ -61,7 +61,7 @@ int gfs2_trans_begin(struct gfs2_sbd *sd
goto fail_gunlock;
}
- error = gfs2_log_reserve(sdp, tr->tr_reserved);
+ error = gfs2_log_reserve(sdp, tr->tr_reserved, wait);
if (error)
goto fail_gunlock;
diff -urpN
--exclude-from=linux-2.6.18-44.gfs2abhi.003_test_clean/Documentation/dontdiff
linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/trans.h
linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/trans.h
--- linux-2.6.18-44.gfs2abhi.003_test_clean/fs/gfs2/trans.h 2007-09-04
07:45:25.000000000 -0500
+++ linux-2.6.18-44.gfs2abhi.003_test/fs/gfs2/trans.h 2007-09-09
08:21:29.000000000 -0500
@@ -25,8 +25,8 @@ struct gfs2_glock;
#define RES_STATFS 1
#define RES_QUOTA 2
-int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
- unsigned int revokes);
+int gfs2_do_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
+ unsigned int revokes, int wait);
void gfs2_trans_end(struct gfs2_sbd *sdp);
@@ -36,4 +36,11 @@ void gfs2_trans_add_revoke(struct gfs2_s
void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno);
void gfs2_trans_add_rg(struct gfs2_rgrpd *rgd);
+
+static inline int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
+ unsigned int revokes)
+{
+ return gfs2_do_trans_begin(sdp, blocks, revokes, 1);
+}
+
#endif /* __TRANS_DOT_H__ */
