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-rw-r--r--fs/cifs/cifsfs.c7
-rw-r--r--fs/dcache.c6
-rw-r--r--fs/debugfs/inode.c6
-rw-r--r--fs/kernfs/mount.c2
-rw-r--r--fs/namei.c56
-rw-r--r--fs/nfsd/nfs3xdr.c4
-rw-r--r--fs/nfsd/nfs4xdr.c11
-rw-r--r--fs/overlayfs/namei.c24
-rw-r--r--fs/quota/dquot.c8
-rw-r--r--include/linux/dcache.h5
-rw-r--r--include/linux/namei.h1
11 files changed, 56 insertions, 74 deletions
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 1d1051d31513..5492b9860baa 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -730,11 +730,6 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
struct inode *dir = d_inode(dentry);
struct dentry *child;
- if (!dir) {
- dput(dentry);
- dentry = ERR_PTR(-ENOENT);
- break;
- }
if (!S_ISDIR(dir->i_mode)) {
dput(dentry);
dentry = ERR_PTR(-ENOTDIR);
@@ -751,7 +746,7 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
while (*s && *s != sep)
s++;
- child = lookup_one_len_unlocked(p, dentry, s - p);
+ child = lookup_positive_unlocked(p, dentry, s - p);
dput(dentry);
dentry = child;
} while (!IS_ERR(dentry));
diff --git a/fs/dcache.c b/fs/dcache.c
index f7931b682a0d..a2749a700230 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -319,7 +319,7 @@ static inline void __d_set_inode_and_type(struct dentry *dentry,
flags = READ_ONCE(dentry->d_flags);
flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
flags |= type_flags;
- WRITE_ONCE(dentry->d_flags, flags);
+ smp_store_release(&dentry->d_flags, flags);
}
static inline void __d_clear_type_and_inode(struct dentry *dentry)
@@ -903,17 +903,19 @@ struct dentry *dget_parent(struct dentry *dentry)
{
int gotref;
struct dentry *ret;
+ unsigned seq;
/*
* Do optimistic parent lookup without any
* locking.
*/
rcu_read_lock();
+ seq = raw_seqcount_begin(&dentry->d_seq);
ret = READ_ONCE(dentry->d_parent);
gotref = lockref_get_not_zero(&ret->d_lockref);
rcu_read_unlock();
if (likely(gotref)) {
- if (likely(ret == READ_ONCE(dentry->d_parent)))
+ if (!read_seqcount_retry(&dentry->d_seq, seq))
return ret;
dput(ret);
}
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 7b975dbb2bb4..f4d8df5e4714 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -299,13 +299,9 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
if (!parent)
parent = debugfs_mount->mnt_root;
- dentry = lookup_one_len_unlocked(name, parent, strlen(name));
+ dentry = lookup_positive_unlocked(name, parent, strlen(name));
if (IS_ERR(dentry))
return NULL;
- if (!d_really_is_positive(dentry)) {
- dput(dentry);
- return NULL;
- }
return dentry;
}
EXPORT_SYMBOL_GPL(debugfs_lookup);
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 4d31503abaee..9dc7e7a64e10 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -223,7 +223,7 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
dput(dentry);
return ERR_PTR(-EINVAL);
}
- dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
+ dtmp = lookup_positive_unlocked(kntmp->name, dentry,
strlen(kntmp->name));
dput(dentry);
if (IS_ERR(dtmp))
diff --git a/fs/namei.c b/fs/namei.c
index 2dda552bcf7a..d6c91d1e88cb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1210,25 +1210,25 @@ static int follow_automount(struct path *path, struct nameidata *nd,
* - Flagged as automount point
*
* This may only be called in refwalk mode.
+ * On success path->dentry is known positive.
*
* Serialization is taken care of in namespace.c
*/
static int follow_managed(struct path *path, struct nameidata *nd)
{
struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
- unsigned managed;
+ unsigned flags;
bool need_mntput = false;
int ret = 0;
/* Given that we're not holding a lock here, we retain the value in a
* local variable for each dentry as we look at it so that we don't see
* the components of that value change under us */
- while (managed = READ_ONCE(path->dentry->d_flags),
- managed &= DCACHE_MANAGED_DENTRY,
- unlikely(managed != 0)) {
+ while (flags = smp_load_acquire(&path->dentry->d_flags),
+ unlikely(flags & DCACHE_MANAGED_DENTRY)) {
/* Allow the filesystem to manage the transit without i_mutex
* being held. */
- if (managed & DCACHE_MANAGE_TRANSIT) {
+ if (flags & DCACHE_MANAGE_TRANSIT) {
BUG_ON(!path->dentry->d_op);
BUG_ON(!path->dentry->d_op->d_manage);
ret = path->dentry->d_op->d_manage(path, false);
@@ -1237,7 +1237,7 @@ static int follow_managed(struct path *path, struct nameidata *nd)
}
/* Transit to a mounted filesystem. */
- if (managed & DCACHE_MOUNTED) {
+ if (flags & DCACHE_MOUNTED) {
struct vfsmount *mounted = lookup_mnt(path);
if (mounted) {
dput(path->dentry);
@@ -1256,7 +1256,7 @@ static int follow_managed(struct path *path, struct nameidata *nd)
}
/* Handle an automount point */
- if (managed & DCACHE_NEED_AUTOMOUNT) {
+ if (flags & DCACHE_NEED_AUTOMOUNT) {
ret = follow_automount(path, nd, &need_mntput);
if (ret < 0)
break;
@@ -1269,10 +1269,12 @@ static int follow_managed(struct path *path, struct nameidata *nd)
if (need_mntput && path->mnt == mnt)
mntput(path->mnt);
- if (ret == -EISDIR || !ret)
- ret = 1;
if (need_mntput)
nd->flags |= LOOKUP_JUMPED;
+ if (ret == -EISDIR || !ret)
+ ret = 1;
+ if (ret > 0 && unlikely(d_flags_negative(flags)))
+ ret = -ENOENT;
if (unlikely(ret < 0))
path_put_conditional(path, nd);
return ret;
@@ -1621,10 +1623,6 @@ static int lookup_fast(struct nameidata *nd,
dput(dentry);
return status;
}
- if (unlikely(d_is_negative(dentry))) {
- dput(dentry);
- return -ENOENT;
- }
path->mnt = mnt;
path->dentry = dentry;
@@ -1811,11 +1809,6 @@ static int walk_component(struct nameidata *nd, int flags)
if (unlikely(err < 0))
return err;
- if (unlikely(d_is_negative(path.dentry))) {
- path_to_nameidata(&path, nd);
- return -ENOENT;
- }
-
seq = 0; /* we are already out of RCU mode */
inode = d_backing_inode(path.dentry);
}
@@ -2568,6 +2561,26 @@ struct dentry *lookup_one_len_unlocked(const char *name,
}
EXPORT_SYMBOL(lookup_one_len_unlocked);
+/*
+ * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT)
+ * on negatives. Returns known positive or ERR_PTR(); that's what
+ * most of the users want. Note that pinned negative with unlocked parent
+ * _can_ become positive at any time, so callers of lookup_one_len_unlocked()
+ * need to be very careful; pinned positives have ->d_inode stable, so
+ * this one avoids such problems.
+ */
+struct dentry *lookup_positive_unlocked(const char *name,
+ struct dentry *base, int len)
+{
+ struct dentry *ret = lookup_one_len_unlocked(name, base, len);
+ if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
+ dput(ret);
+ ret = ERR_PTR(-ENOENT);
+ }
+ return ret;
+}
+EXPORT_SYMBOL(lookup_positive_unlocked);
+
#ifdef CONFIG_UNIX98_PTYS
int path_pts(struct path *path)
{
@@ -2662,7 +2675,7 @@ mountpoint_last(struct nameidata *nd)
return PTR_ERR(path.dentry);
}
}
- if (d_is_negative(path.dentry)) {
+ if (d_flags_negative(smp_load_acquire(&path.dentry->d_flags))) {
dput(path.dentry);
return -ENOENT;
}
@@ -3356,11 +3369,6 @@ static int do_last(struct nameidata *nd,
if (unlikely(error < 0))
return error;
- if (unlikely(d_is_negative(path.dentry))) {
- path_to_nameidata(&path, nd);
- return -ENOENT;
- }
-
/*
* create/update audit record if it already exists.
*/
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 86e5658651f1..195ab7a0fc89 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -863,13 +863,11 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
} else
dchild = dget(dparent);
} else
- dchild = lookup_one_len_unlocked(name, dparent, namlen);
+ dchild = lookup_positive_unlocked(name, dparent, namlen);
if (IS_ERR(dchild))
return rv;
if (d_mountpoint(dchild))
goto out;
- if (d_really_is_negative(dchild))
- goto out;
if (dchild->d_inode->i_ino != ino)
goto out;
rv = fh_compose(fhp, exp, dchild, &cd->fh);
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 533d0fc3c96b..b09237431ae2 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2991,18 +2991,9 @@ nfsd4_encode_dirent_fattr(struct xdr_stream *xdr, struct nfsd4_readdir *cd,
__be32 nfserr;
int ignore_crossmnt = 0;
- dentry = lookup_one_len_unlocked(name, cd->rd_fhp->fh_dentry, namlen);
+ dentry = lookup_positive_unlocked(name, cd->rd_fhp->fh_dentry, namlen);
if (IS_ERR(dentry))
return nfserrno(PTR_ERR(dentry));
- if (d_really_is_negative(dentry)) {
- /*
- * we're not holding the i_mutex here, so there's
- * a window where this directory entry could have gone
- * away.
- */
- dput(dentry);
- return nfserr_noent;
- }
exp_get(exp);
/*
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index e9717c2f7d45..c269d6033525 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -200,7 +200,7 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
int err;
bool last_element = !post[0];
- this = lookup_one_len_unlocked(name, base, namelen);
+ this = lookup_positive_unlocked(name, base, namelen);
if (IS_ERR(this)) {
err = PTR_ERR(this);
this = NULL;
@@ -208,8 +208,6 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
goto out;
goto out_err;
}
- if (!this->d_inode)
- goto put_and_out;
if (ovl_dentry_weird(this)) {
/* Don't support traversing automounts and other weirdness */
@@ -651,7 +649,7 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
if (err)
return ERR_PTR(err);
- index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
kfree(name.name);
if (IS_ERR(index)) {
if (PTR_ERR(index) == -ENOENT)
@@ -659,9 +657,7 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
return index;
}
- if (d_is_negative(index))
- err = 0;
- else if (ovl_is_whiteout(index))
+ if (ovl_is_whiteout(index))
err = -ESTALE;
else if (ovl_dentry_weird(index))
err = -EIO;
@@ -685,7 +681,7 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
if (err)
return ERR_PTR(err);
- index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len);
if (IS_ERR(index)) {
err = PTR_ERR(index);
if (err == -ENOENT) {
@@ -700,9 +696,7 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
}
inode = d_inode(index);
- if (d_is_negative(index)) {
- goto out_dput;
- } else if (ovl_is_whiteout(index) && !verify) {
+ if (ovl_is_whiteout(index) && !verify) {
/*
* When index lookup is called with !verify for decoding an
* overlay file handle, a whiteout index implies that decode
@@ -1131,7 +1125,7 @@ bool ovl_lower_positive(struct dentry *dentry)
struct dentry *this;
struct dentry *lowerdir = poe->lowerstack[i].dentry;
- this = lookup_one_len_unlocked(name->name, lowerdir,
+ this = lookup_positive_unlocked(name->name, lowerdir,
name->len);
if (IS_ERR(this)) {
switch (PTR_ERR(this)) {
@@ -1148,10 +1142,8 @@ bool ovl_lower_positive(struct dentry *dentry)
break;
}
} else {
- if (this->d_inode) {
- positive = !ovl_is_whiteout(this);
- done = true;
- }
+ positive = !ovl_is_whiteout(this);
+ done = true;
dput(this);
}
}
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 4639d53e96a3..b0688c02dc90 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2487,21 +2487,15 @@ int dquot_quota_on_mount(struct super_block *sb, char *qf_name,
struct dentry *dentry;
int error;
- dentry = lookup_one_len_unlocked(qf_name, sb->s_root, strlen(qf_name));
+ dentry = lookup_positive_unlocked(qf_name, sb->s_root, strlen(qf_name));
if (IS_ERR(dentry))
return PTR_ERR(dentry);
- if (d_really_is_negative(dentry)) {
- error = -ENOENT;
- goto out;
- }
-
error = security_quota_on(dentry);
if (!error)
error = dquot_load_quota_inode(d_inode(dentry), type, format_id,
DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
-out:
dput(dentry);
return error;
}
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 10090f11ab95..c1488cc84fd9 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -440,6 +440,11 @@ static inline bool d_is_negative(const struct dentry *dentry)
return d_is_miss(dentry);
}
+static inline bool d_flags_negative(unsigned flags)
+{
+ return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE;
+}
+
static inline bool d_is_positive(const struct dentry *dentry)
{
return !d_is_negative(dentry);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 397a08ade6a2..7fe7b87a3ded 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -60,6 +60,7 @@ extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
+extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
extern int follow_down_one(struct path *);
extern int follow_down(struct path *);
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