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authorBob Peterson <rpeterso@redhat.com>2014-08-20 12:44:45 -0400
committerSteven Whitehouse <swhiteho@redhat.com>2014-08-21 10:22:52 +0100
commit2ddfbdd6848d496d8088b28992d257fd02e58c9d (patch)
tree58ba5b778b6cb26bcafe52fb7034480a4c68af45 /fs/gfs2
parentb650738cd093a9f9e9551db9ce5cd68acd842dc0 (diff)
GFS2: Request demote when a "try" flock fails
This patch changes the flock code so that it uses the TRY_1CB flag instead of the TRY flag on the first attempt. That forces any holding nodes to issue a dlm callback, which requests a demote of the glock. Then, if the "try" failed, it sleeps a small amount of time for the demote to occur. Then it tries again, for an increasing amount of time. Subsequent attempts to gain the "try" lock don't use "_1CB" so that only one callback is issued. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2')
-rw-r--r--fs/gfs2/file.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 26b3f952e6b1..7f4ed3daa38c 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -26,6 +26,7 @@
#include <linux/dlm.h>
#include <linux/dlm_plock.h>
#include <linux/aio.h>
+#include <linux/delay.h>
#include "gfs2.h"
#include "incore.h"
@@ -979,9 +980,10 @@ static int do_flock(struct file *file, int cmd, struct file_lock *fl)
unsigned int state;
int flags;
int error = 0;
+ int sleeptime;
state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED;
- flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT;
+ flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY_1CB) | GL_EXACT;
mutex_lock(&fp->f_fl_mutex);
@@ -1001,7 +1003,14 @@ static int do_flock(struct file *file, int cmd, struct file_lock *fl)
gfs2_holder_init(gl, state, flags, fl_gh);
gfs2_glock_put(gl);
}
- error = gfs2_glock_nq(fl_gh);
+ for (sleeptime = 1; sleeptime <= 4; sleeptime <<= 1) {
+ error = gfs2_glock_nq(fl_gh);
+ if (error != GLR_TRYFAILED)
+ break;
+ fl_gh->gh_flags = LM_FLAG_TRY | GL_EXACT;
+ fl_gh->gh_error = 0;
+ msleep(sleeptime);
+ }
if (error) {
gfs2_holder_uninit(fl_gh);
if (error == GLR_TRYFAILED)
@@ -1024,7 +1033,7 @@ static void do_unflock(struct file *file, struct file_lock *fl)
mutex_lock(&fp->f_fl_mutex);
flock_lock_file_wait(file, fl);
if (fl_gh->gh_gl) {
- gfs2_glock_dq_wait(fl_gh);
+ gfs2_glock_dq(fl_gh);
gfs2_holder_uninit(fl_gh);
}
mutex_unlock(&fp->f_fl_mutex);