In afs_linux_lookup, we try to invalidate as many dentry aliases as we
can. However, a successful d_invalidate() against a dentry does not
necessarily mean that the dentry will not show up in a later
d_find_alias() call. This is because d_invalidate() does not remove
the dentry from the d_alias list, but just removes it from the hash
chain. dput() is what removes it from the d_alias list when all of the
references go away. If a reference is grabbed between our
d_invalidate() and dput() calls, the dentry will stay on the d_alias
list.
We will then retry the loop, and we will get the same dentry back from
d_find_alias(). Running d_invalidate() on an unhashed dentry is a
no-op, so we don't change anything in the loop. We will retry again
and again, looping forever and spinning the CPU.
To avoid this, just call d_prune_aliases instead, instead of
repeatedly looping through the alias list ourselves. Note that this
does remove our check for DCACHE_DISCONNECTED in each alias' d_flags.
This should not be a problem, since we will still use any remaining
DCACHE_DISCONNECTED dentry via d_splice_alias if one still exists.
Change-Id: I8a09a922d07f2c4971269f3c681c748c33bf8e3d
Reviewed-on: http://gerrit.openafs.org/8751
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
AFS_GUNLOCK();
if (ip && S_ISDIR(ip->i_mode)) {
- int retry = 1;
- struct dentry *alias;
-
- while (retry) {
- retry = 0;
-
- /* Try to invalidate an existing alias in favor of our new one */
- alias = d_find_alias(ip);
- /* But not if it's disconnected; then we want d_splice_alias below */
- if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {
- if (d_invalidate(alias) == 0) {
- /* there may be more aliases; try again until we run out */
- retry = 1;
- }
- }
-
- dput(alias);
- }
+ d_prune_aliases(ip);
#ifdef STRUCT_DENTRY_OPERATIONS_HAS_D_AUTOMOUNT
ip->i_flags |= S_AUTOMOUNT;
#if defined(AFS_LINUX24_ENV)
if (ip && S_ISDIR(ip->i_mode)) {
- int retry = 1;
- struct dentry *alias;
-
- while (retry) {
- retry = 0;
-
- /* Try to invalidate an existing alias in favor of our new one */
- alias = d_find_alias(ip);
- /* But not if it's disconnected; then we want d_splice_alias below */
- if (alias) {
- if (d_invalidate(alias) == 0) {
- /* there may be more aliases; try again until we run out */
- retry = 1;
- }
- }
-
- dput(alias);
- }
+ d_prune_aliases(ip);
}
#endif
d_add(dp, ip);