From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
There are a few d_obtain_alias callers that are using it to get the
root of a filesystem which may already have an alias somewhere else.
This is not the same as the filehandle-lookup case, and none of them
actually need DCACHE_DISCONNECTED set.
It isn't really a serious problem, but it would really be clearer if we
reserved DCACHE_DISCONNECTED for those cases where it's actually needed.
In the btrfs case this was causing a spurious printk from
nfsd/nfsfh.c:fh_verify when it found an unexpected DCACHE_DISCONNECTED
dentry. Josef worked around this by unsetting DCACHE_DISCONNECTED
manually in 3a0dfa6a12e "Btrfs: unset DCACHE_DISCONNECTED when mounting
default subvol", and this replaces that workaround.
Cc: Josef Bacik <jbacik@xxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
---
fs/btrfs/super.c | 9 +------
fs/ceph/super.c | 2 +-
fs/dcache.c | 69 ++++++++++++++++++++++++++++++++++--------------
fs/nfs/getroot.c | 2 +-
fs/nilfs2/super.c | 2 +-
include/linux/dcache.h | 1 +
6 files changed, 54 insertions(+), 31 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9601d25..b05588b 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -843,7 +843,6 @@ static struct dentry *get_default_root(struct super_block *sb,
struct btrfs_path *path;
struct btrfs_key location;
struct inode *inode;
- struct dentry *dentry;
u64 dir_id;
int new = 0;
@@ -914,13 +913,7 @@ setup_root:
return dget(sb->s_root);
}
- dentry = d_obtain_alias(inode);
- if (!IS_ERR(dentry)) {
- spin_lock(&dentry->d_lock);
- dentry->d_flags &= ~DCACHE_DISCONNECTED;
- spin_unlock(&dentry->d_lock);
- }
- return dentry;
+ return d_obtain_root(inode);
}
static int btrfs_fill_super(struct super_block *sb,
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 06150fd..f6e1237 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -755,7 +755,7 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
goto out;
}
} else {
- root = d_obtain_alias(inode);
+ root = d_obtain_root(inode);
}
ceph_init_dentry(root);
dout("open_root_inode success, root dentry is %p\n", root);
diff --git a/fs/dcache.c b/fs/dcache.c
index c42009f..5a8517f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1718,25 +1718,7 @@ struct dentry *d_find_any_alias(struct inode *inode)
}
EXPORT_SYMBOL(d_find_any_alias);
-/**
- * d_obtain_alias - find or allocate a dentry for a given inode
- * @inode: inode to allocate the dentry for
- *
- * Obtain a dentry for an inode resulting from NFS filehandle conversion or
- * similar open by handle operations. The returned dentry may be anonymous,
- * or may have a full name (if the inode was already in the cache).
- *
- * When called on a directory inode, we must ensure that the inode only ever
- * has one dentry. If a dentry is found, that is returned instead of
- * allocating a new one.
- *
- * On successful return, the reference to the inode has been transferred
- * to the dentry. In case of an error the reference on the inode is released.
- * To make it easier to use in export operations a %NULL or IS_ERR inode may
- * be passed in and will be the error will be propagate to the return value,
- * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
- */
-struct dentry *d_obtain_alias(struct inode *inode)
+struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
{
static const struct qstr anonstring = QSTR_INIT("/", 1);
struct dentry *tmp;
@@ -1767,7 +1749,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
}
/* attach a disconnected dentry */
- add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED;
+ add_flags = d_flags_for_inode(inode);
+
+ if (disconnected)
+ add_flags |= DCACHE_DISCONNECTED;
spin_lock(&tmp->d_lock);
tmp->d_inode = inode;
@@ -1788,9 +1773,53 @@ struct dentry *d_obtain_alias(struct inode *inode)
iput(inode);
return res;
}
+
+/**
+ * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
+ * @inode: inode to allocate the dentry for
+ *
+ * Obtain a dentry for an inode resulting from NFS filehandle conversion or
+ * similar open by handle operations. The returned dentry may be anonymous,
+ * or may have a full name (if the inode was already in the cache).
+ *
+ * When called on a directory inode, we must ensure that the inode only ever
+ * has one dentry. If a dentry is found, that is returned instead of
+ * allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry. In case of an error the reference on the inode is released.
+ * To make it easier to use in export operations a %NULL or IS_ERR inode may
+ * be passed in and the error will be propagated to the return value,
+ * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
+ */
+struct dentry *d_obtain_alias(struct inode *inode)
+{
+ return __d_obtain_alias(inode, 1);
+}
EXPORT_SYMBOL(d_obtain_alias);
/**
+ * d_obtain_root - find or allocate a dentry for a given inode
+ * @inode: inode to allocate the dentry for
+ *
+ * Obtain an IS_ROOT dentry for the root of a filesystem.
+ *
+ * We must ensure that directory inodes only ever have one dentry. If a
+ * dentry is found, that is returned instead of allocating a new one.
+ *
+ * On successful return, the reference to the inode has been transferred
+ * to the dentry. In case of an error the reference on the inode is
+ * released. A %NULL or IS_ERR inode may be passed in and will be the
+ * error will be propagate to the return value, with a %NULL @inode
+ * replaced by ERR_PTR(-ESTALE).
+ */
+struct dentry *d_obtain_root(struct inode *inode)
+{
+ return __d_obtain_alias(inode, 0);
+}
+EXPORT_SYMBOL(d_obtain_root);
+
+/**
* d_add_ci - lookup or allocate new dentry with case-exact name
* @inode: the inode case-insensitive lookup has found
* @dentry: the negative dentry that was passed to the parent's lookup func
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index 66984a9..e851f53 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -112,7 +112,7 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
* if the dentry tree reaches them; however if the dentry already
* exists, we'll pick it up at this point and use it as the root
*/
- ret = d_obtain_alias(inode);
+ ret = d_obtain_root(inode);
if (IS_ERR(ret)) {
dprintk("nfs_get_root: get root dentry failed\n");
goto out;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 8c532b2..ac91499 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -942,7 +942,7 @@ static int nilfs_get_root_dentry(struct super_block *sb,
iput(inode);
}
} else {
- dentry = d_obtain_alias(inode);
+ dentry = d_obtain_root(inode);
if (IS_ERR(dentry)) {
ret = PTR_ERR(dentry);
goto failed_dentry;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 3c7ec32..e4ae2ad 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -249,6 +249,7 @@ extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
extern struct dentry *d_find_any_alias(struct inode *inode);
extern struct dentry * d_obtain_alias(struct inode *);
+extern struct dentry * d_obtain_root(struct inode *);
extern void shrink_dcache_sb(struct super_block *);
extern void shrink_dcache_parent(struct dentry *);
extern void shrink_dcache_for_umount(struct super_block *);
--
1.7.9.5
--
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