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08-09-2012 05:48 PM

GFS2: Eliminate redundant calls to may_grant
 
From: Bob Peterson <rpeterso@redhat.com>

Function add_to_queue was checking may_grant for the passed-in
holder for every iteration of its gh2 loop. Now it only checks it
once at the beginning to see if a try lock is futile.
---
fs/gfs2/glock.c | 9 ++++-----
1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index fca6a87..e6c2fd5 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -954,7 +954,7 @@ __acquires(&gl->gl_spin)
struct gfs2_sbd *sdp = gl->gl_sbd;
struct list_head *insert_pt = NULL;
struct gfs2_holder *gh2;
- int try_lock = 0;
+ int try_futile = 0;

BUG_ON(gh->gh_owner_pid == NULL);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
@@ -962,7 +962,7 @@ __acquires(&gl->gl_spin)

if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
if (test_bit(GLF_LOCK, &gl->gl_flags))
- try_lock = 1;
+ try_futile = !may_grant(gl, gh);
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
goto fail;
}
@@ -971,9 +971,8 @@ __acquires(&gl->gl_spin)
if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
(gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
goto trap_recursive;
- if (try_lock &&
- !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
- !may_grant(gl, gh)) {
+ if (try_futile &&
+ !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
fail:
gh->gh_error = GLR_TRYFAILED;
gfs2_holder_wake(gh);
--
1.7.7.6

Steven Whitehouse 09-26-2012 08:25 AM

GFS2: Eliminate redundant calls to may_grant
 
From: Bob Peterson <rpeterso@redhat.com>

Function add_to_queue was checking may_grant for the passed-in
holder for every iteration of its gh2 loop. Now it only checks it
once at the beginning to see if a try lock is futile.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index fca6a87..e6c2fd5 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -954,7 +954,7 @@ __acquires(&gl->gl_spin)
struct gfs2_sbd *sdp = gl->gl_sbd;
struct list_head *insert_pt = NULL;
struct gfs2_holder *gh2;
- int try_lock = 0;
+ int try_futile = 0;

BUG_ON(gh->gh_owner_pid == NULL);
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
@@ -962,7 +962,7 @@ __acquires(&gl->gl_spin)

if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
if (test_bit(GLF_LOCK, &gl->gl_flags))
- try_lock = 1;
+ try_futile = !may_grant(gl, gh);
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
goto fail;
}
@@ -971,9 +971,8 @@ __acquires(&gl->gl_spin)
if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
(gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
goto trap_recursive;
- if (try_lock &&
- !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
- !may_grant(gl, gh)) {
+ if (try_futile &&
+ !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
fail:
gh->gh_error = GLR_TRYFAILED;
gfs2_holder_wake(gh);
--
1.7.4


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