path: root/fs/autofs4/expire.c
diff options
authorNeilBrown <neilb@suse.de>2014-10-13 15:52:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-14 02:18:16 +0200
commit23bfc2a24ea3d993cc5cc90c9970654e7232502e (patch)
treea2bc0e834578b8b8559e255363e9b95d08158e97 /fs/autofs4/expire.c
parentfs/ncpfs/dir.c: remove redundant sys_tz declaration (diff)
autofs4: allow RCU-walk to walk through autofs4
This series teaches autofs about RCU-walk so that we don't drop straight into REF-walk when we hit an autofs directory, and so that we avoid spinlocks as much as possible when performing an RCU-walk. This is needed so that the benefits of the recent NFS support for RCU-walk are fully available when NFS filesystems are automounted. Patches have been carefully reviewed and tested both with test suites and in production - thanks a lot to Ian Kent for his support there. This patch (of 6): Any attempt to look up a pathname that passes though an autofs4 mount is currently forced out of RCU-walk into REF-walk. This can significantly hurt performance of many-thread work loads on many-core systems, especially if the automounted filesystem supports RCU-walk but doesn't get to benefit from it. So if autofs4_d_manage is called with rcu_walk set, only fail with -ECHILD if it is necessary to wait longer than a spinlock. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Ian Kent <raven@themaw.net> Tested-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/autofs4/expire.c')
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 8fa3895cda02..1695eda8ac18 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -461,7 +461,7 @@ found:
return expired;
-int autofs4_expire_wait(struct dentry *dentry)
+int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
struct autofs_info *ino = autofs4_dentry_ino(dentry);
@@ -471,6 +471,8 @@ int autofs4_expire_wait(struct dentry *dentry)
if (ino->flags & AUTOFS_INF_EXPIRING) {
+ if (rcu_walk)
+ return -ECHILD;
DPRINTK("waiting for expire %p name=%.*s",
dentry, dentry->d_name.len, dentry->d_name.name);