path: root/fs/gfs2/glock.c
diff options
authorSteven Whitehouse <>2008-07-07 10:07:28 +0100
committerSteven Whitehouse <>2008-07-07 10:07:28 +0100
commit209806aba9d540dde3db0a5ce72307f85f33468f (patch)
tree22543b35c6b06d9a736c1c9af881ea7cf305d2bd /fs/gfs2/glock.c
parent265d529cef6fd57698d79b3c0edd3a8178059ea6 (diff)
[GFS2] Allow local DF locks when holding a cached EX glock
We already allow local SH locks while we hold a cached EX glock, so here we allow DF locks as well. This works only because we rely on the VFS's invalidation for locally cached data, and because if we hold an EX lock, then we know that no other node can be caching data relating to this file. It dramatically speeds up initial writes to O_DIRECT files since we fall back to buffered I/O for this and would otherwise bounce between DF and EX modes on each and every write call. The lessons to be learned from that are to ensure that (for the time being anyway) O_DIRECT files are preallocated and that they are written to using reasonably large I/O sizes. Even so this change fixes that corner case nicely Signed-off-by: Steven Whitehouse <>
Diffstat (limited to 'fs/gfs2/glock.c')
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index cd0aa213fb2..13391e54661 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -267,8 +267,12 @@ static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holde
return 1;
if (gh->gh_flags & GL_EXACT)
return 0;
- if (gh->gh_state == LM_ST_SHARED && gl->gl_state == LM_ST_EXCLUSIVE)
- return 1;
+ if (gl->gl_state == LM_ST_EXCLUSIVE) {
+ if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
+ return 1;
+ if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
+ return 1;
+ }
if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
return 1;
return 0;