From dcfbe9a59979e9e48dae79bd3525d10c71b9fe50 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 17 Sep 2012 22:31:38 +0200 Subject: [PATCH] vfs: dcache: use DCACHE_DENTRY_KILLED instead of DCACHE_DISCONNECTED in d_kill() commit b161dfa6937ae46d50adce8a7c6b12233e96e7bd upstream. IBM reported a soft lockup after applying the fix for the rename_lock deadlock. Commit c83ce989cb5f ("VFS: Fix the nfs sillyrename regression in kernel 2.6.38") was found to be the culprit. The nfs sillyrename fix used DCACHE_DISCONNECTED to indicate that the dentry was killed. This flag can be set on non-killed dentries too, which results in infinite retries when trying to traverse the dentry tree. This patch introduces a separate flag: DCACHE_DENTRY_KILLED, which is only set in d_kill() and makes try_to_ascend() test only this flag. IBM reported successful test results with this patch. Signed-off-by: Miklos Szeredi Cc: Trond Myklebust Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/dcache.c | 4 ++-- include/linux/dcache.h | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 40469044088d..4123b92823fc 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -389,7 +389,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) * Inform try_to_ascend() that we are no longer attached to the * dentry tree */ - dentry->d_flags |= DCACHE_DISCONNECTED; + dentry->d_flags |= DCACHE_DENTRY_KILLED; if (parent) spin_unlock(&parent->d_lock); dentry_iput(dentry); @@ -1046,7 +1046,7 @@ static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq * or deletion */ if (new != old->d_parent || - (old->d_flags & DCACHE_DISCONNECTED) || + (old->d_flags & DCACHE_DENTRY_KILLED) || (!locked && read_seqretry(&rename_lock, seq))) { spin_unlock(&new->d_lock); new = NULL; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 094789ff3e9f..525ab1260113 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -206,6 +206,8 @@ struct dentry_operations { #define DCACHE_MANAGED_DENTRY \ (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) +#define DCACHE_DENTRY_KILLED 0x100000 + extern seqlock_t rename_lock; static inline int dname_external(struct dentry *dentry) -- 2.39.5