From 1a0a397e41cb1bf70cfe45fd0eeff08c7c501ec0 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Fri, 14 Feb 2014 17:35:37 -0500 Subject: [PATCH] dcache: d_obtain_alias callers don't all want DISCONNECTED 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 Signed-off-by: J. Bruce Fields Signed-off-by: Al Viro --- 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 8e16bca69c56..67b48b9a03e0 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -851,7 +851,6 @@ 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; @@ -922,13 +921,7 @@ 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 06150fd745ac..f6e12377335c 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 3ed095363997..63d556c0e698 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1781,25 +1781,7 @@ 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; @@ -1830,7 +1812,10 @@ 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; @@ -1851,8 +1836,52 @@ 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 diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c index b94f80420a58..880618a8b048 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 8c532b2ca3ab..ac914994dfed 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 3c7ec327ebd2..e4ae2ad48d07 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 *); -- 2.30.2