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authorNick Piggin <npiggin@kernel.dk>2011-01-07 09:49:57 +0300
committerNick Piggin <npiggin@kernel.dk>2011-01-07 09:50:29 +0300
commit34286d6662308d82aed891852d04c7c3a2649b16 (patch)
treec4b7311404d302e7cb94df7a4690298e1059910a /fs/namei.c
parent44a7d7a878c9cbb74f236ea755b25b6b2e26a9a9 (diff)
downloadlinux-34286d6662308d82aed891852d04c7c3a2649b16.tar.xz
fs: rcu-walk aware d_revalidate method
Require filesystems be aware of .d_revalidate being called in rcu-walk mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning -ECHILD from all implementations. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c54
1 files changed, 36 insertions, 18 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 90bd2873e117..6e275363e89d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -563,10 +563,26 @@ void release_open_intent(struct nameidata *nd)
fput(nd->intent.open.file);
}
+static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ int status;
+
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ if (status == -ECHILD) {
+ if (nameidata_dentry_drop_rcu(nd, dentry))
+ return status;
+ status = dentry->d_op->d_revalidate(dentry, nd);
+ }
+
+ return status;
+}
+
static inline struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- int status = dentry->d_op->d_revalidate(dentry, nd);
+ int status;
+
+ status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
/*
* The dentry failed validation.
@@ -574,14 +590,20 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
* the dentry otherwise d_revalidate is asking us
* to return a fail status.
*/
- if (!status) {
+ if (status < 0) {
+ /* If we're in rcu-walk, we don't have a ref */
+ if (!(nd->flags & LOOKUP_RCU))
+ dput(dentry);
+ dentry = ERR_PTR(status);
+
+ } else {
+ /* Don't d_invalidate in rcu-walk mode */
+ if (nameidata_dentry_drop_rcu_maybe(nd, dentry))
+ return ERR_PTR(-ECHILD);
if (!d_invalidate(dentry)) {
dput(dentry);
dentry = NULL;
}
- } else {
- dput(dentry);
- dentry = ERR_PTR(status);
}
}
return dentry;
@@ -626,7 +648,7 @@ force_reval_path(struct path *path, struct nameidata *nd)
if (!need_reval_dot(dentry))
return 0;
- status = dentry->d_op->d_revalidate(dentry, nd);
+ status = d_revalidate(dentry, nd);
if (status > 0)
return 0;
@@ -1039,12 +1061,8 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
return -ECHILD;
nd->seq = seq;
- if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
- /* We commonly drop rcu-walk here */
- if (nameidata_dentry_drop_rcu(nd, dentry))
- return -ECHILD;
+ if (dentry->d_flags & DCACHE_OP_REVALIDATE)
goto need_revalidate;
- }
path->mnt = mnt;
path->dentry = dentry;
__follow_mount_rcu(nd, path, inode);
@@ -1292,12 +1310,11 @@ return_reval:
* We may need to check the cached dentry for staleness.
*/
if (need_reval_dot(nd->path.dentry)) {
- if (nameidata_drop_rcu_maybe(nd))
- return -ECHILD;
- err = -ESTALE;
/* Note: we do not d_invalidate() */
- if (!nd->path.dentry->d_op->d_revalidate(
- nd->path.dentry, nd))
+ err = d_revalidate(nd->path.dentry, nd);
+ if (!err)
+ err = -ESTALE;
+ if (err < 0)
break;
}
return_base:
@@ -2080,10 +2097,11 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
dir = nd->path.dentry;
case LAST_DOT:
if (need_reval_dot(dir)) {
- if (!dir->d_op->d_revalidate(dir, nd)) {
+ error = d_revalidate(nd->path.dentry, nd);
+ if (!error)
error = -ESTALE;
+ if (error < 0)
goto exit;
- }
}
/* fallthrough */
case LAST_ROOT: