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authorSteven Whitehouse <swhiteho@redhat.com>2008-02-22 16:07:18 +0000
committerSteven Whitehouse <swhiteho@redhat.com>2008-03-31 10:41:12 +0100
commit7afd88d9166a752b52517648bcbe923e05d393fc (patch)
tree2fb945189e3cb1be7ad007088f8ec86e9f67ece6 /fs/gfs2/ops_dentry.c
parent60b779cfc1fa52034a996ee12a23b62d32e86000 (diff)
[GFS2] Fix a page lock / glock deadlock
We've previously been using a "try lock" in readpage on the basis that it would prevent deadlocks due to the inverted lock ordering (our normal lock ordering is glock first and then page lock). Unfortunately tests have shown that this isn't enough. If the glock has a demote request queued such that run_queue() in the glock code tries to do a demote when its called under readpage then it will try and write out all the dirty pages which requires locking them. This then deadlocks with the page locked by readpage. The solution is to always require two calls into readpage. The first unlocks the page, gets the glock and returns AOP_TRUNCATED_PAGE, the second does the actual readpage and unlocks the glock & page as required. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2/ops_dentry.c')
-rw-r--r--fs/gfs2/ops_dentry.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/gfs2/ops_dentry.c b/fs/gfs2/ops_dentry.c
index 793e334d098e..4a5e676b4420 100644
--- a/fs/gfs2/ops_dentry.c
+++ b/fs/gfs2/ops_dentry.c
@@ -43,7 +43,7 @@ static int gfs2_drevalidate(struct dentry *dentry, struct nameidata *nd)
struct gfs2_holder d_gh;
struct gfs2_inode *ip = NULL;
int error;
- int had_lock=0;
+ int had_lock = 0;
if (inode) {
if (is_bad_inode(inode))
@@ -54,7 +54,7 @@ static int gfs2_drevalidate(struct dentry *dentry, struct nameidata *nd)
if (sdp->sd_args.ar_localcaching)
goto valid;
- had_lock = gfs2_glock_is_locked_by_me(dip->i_gl);
+ had_lock = (gfs2_glock_is_locked_by_me(dip->i_gl) != NULL);
if (!had_lock) {
error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &d_gh);
if (error)