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Message-ID: <20250822000818.1086550-14-neil@brown.name>
Date: Fri, 22 Aug 2025 10:00:31 +1000
From: NeilBrown <neil@...wn.name>
To: Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>
Cc: Jan Kara <jack@...e.cz>,
linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 13/16] VFS/nfsd/cachefiles: introduce start_removing()
start_removing() is similar to start_creating() to will only return a
positive dentry and the expectation is that it will be removed.
This is used by nfsd and cachefiles. They are changed to also
use end_dirop() to terminate the action begun by start_removing().
Signed-off-by: NeilBrown <neil@...wn.name>
---
fs/cachefiles/namei.c | 25 ++++++++++---------------
fs/namei.c | 27 +++++++++++++++++++++++++++
fs/nfsd/nfs4recover.c | 24 +++++++-----------------
fs/nfsd/vfs.c | 26 ++++++++++----------------
include/linux/namei.h | 2 ++
5 files changed, 56 insertions(+), 48 deletions(-)
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 9af324473967..ddced50afb66 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -260,6 +260,7 @@ static int cachefiles_unlink(struct cachefiles_cache *cache,
* - File backed objects are unlinked
* - Directory backed objects are stuffed into the graveyard for userspace to
* delete
+ * On entry dir must be locked. It will be unlocked on exit.
*/
int cachefiles_bury_object(struct cachefiles_cache *cache,
struct cachefiles_object *object,
@@ -275,7 +276,8 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,
_enter(",'%pd','%pd'", dir, rep);
if (rep->d_parent != dir) {
- inode_unlock(d_inode(dir));
+ dget(rep);
+ end_dirop(rep);
_leave(" = -ESTALE");
return -ESTALE;
}
@@ -286,16 +288,16 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,
* by a file struct.
*/
ret = cachefiles_unlink(cache, object, dir, rep, why);
- dput(rep);
+ end_dirop(rep);
- inode_unlock(d_inode(dir));
_leave(" = %d", ret);
return ret;
}
/* directories have to be moved to the graveyard */
_debug("move stale object to graveyard");
- inode_unlock(d_inode(dir));
+ dget(rep);
+ end_dirop(rep);
try_again:
/* first step is to make up a grave dentry in the graveyard */
@@ -745,26 +747,20 @@ static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache,
struct dentry *victim;
int ret = -ENOENT;
- inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
+ victim = start_removing(&nop_mnt_idmap, dir, &QSTR(filename));
- victim = lookup_one(&nop_mnt_idmap, &QSTR(filename), dir);
if (IS_ERR(victim))
goto lookup_error;
- if (d_is_negative(victim))
- goto lookup_put;
if (d_inode(victim)->i_flags & S_KERNEL_FILE)
goto lookup_busy;
return victim;
lookup_busy:
ret = -EBUSY;
-lookup_put:
- inode_unlock(d_inode(dir));
- dput(victim);
+ end_dirop(victim);
return ERR_PTR(ret);
lookup_error:
- inode_unlock(d_inode(dir));
ret = PTR_ERR(victim);
if (ret == -ENOENT)
return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */
@@ -812,18 +808,17 @@ int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
ret = cachefiles_bury_object(cache, NULL, dir, victim,
FSCACHE_OBJECT_WAS_CULLED);
+ dput(victim);
if (ret < 0)
goto error;
fscache_count_culled();
- dput(victim);
_leave(" = 0");
return 0;
error_unlock:
- inode_unlock(d_inode(dir));
+ end_dirop(victim);
error:
- dput(victim);
if (ret == -ENOENT)
return -ESTALE; /* Probably got retired by the netfs */
diff --git a/fs/namei.c b/fs/namei.c
index 407f3516b335..27a99c276137 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3186,6 +3186,33 @@ struct dentry *start_creating(struct mnt_idmap *idmap, struct dentry *parent,
}
EXPORT_SYMBOL(start_creating);
+/**
+ * start_removing - prepare to remove a given name with permission checking
+ * @idmap - idmap of the mount
+ * @parent - directory in which to find the name
+ * @name - the name to be removed
+ *
+ * Locks are taken and a lookup in performed prior to removing
+ * an object from a directory. Permission checking (MAY_EXEC) is performed
+ * against @idmap.
+ *
+ * If the name doesn't exist, an error is returned.
+ *
+ * end_dirop() should be called when removal is complete, or aborted.
+ *
+ * Returns: a positive dentry, or an error.
+ */
+struct dentry *start_removing(struct mnt_idmap *idmap, struct dentry *parent,
+ struct qstr *name)
+{
+ int err = lookup_one_common(idmap, name, parent);
+
+ if (err)
+ return ERR_PTR(err);
+ return start_dirop(parent, name, 0);
+}
+EXPORT_SYMBOL(start_removing);
+
#ifdef CONFIG_UNIX98_PTYS
int path_pts(struct path *path)
{
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index f65cf7ecea6d..8d4bb22db3b7 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -335,20 +335,12 @@ nfsd4_unlink_clid_dir(char *name, struct nfsd_net *nn)
dprintk("NFSD: nfsd4_unlink_clid_dir. name %s\n", name);
dir = nn->rec_file->f_path.dentry;
- inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
- dentry = lookup_one(&nop_mnt_idmap, &QSTR(name), dir);
- if (IS_ERR(dentry)) {
- status = PTR_ERR(dentry);
- goto out_unlock;
- }
- status = -ENOENT;
- if (d_really_is_negative(dentry))
- goto out;
+ dentry = start_removing(&nop_mnt_idmap, dir, &QSTR(name));
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
status = vfs_rmdir(&nop_mnt_idmap, d_inode(dir), dentry);
-out:
- dput(dentry);
-out_unlock:
- inode_unlock(d_inode(dir));
+ end_dirop(dentry);
return status;
}
@@ -435,16 +427,14 @@ purge_old(struct dentry *parent, char *cname, struct nfsd_net *nn)
if (nfs4_has_reclaimed_state(name, nn))
goto out_free;
- inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
- child = lookup_one(&nop_mnt_idmap, &QSTR(cname), parent);
+ child = start_removing(&nop_mnt_idmap, parent, &QSTR(cname));
if (!IS_ERR(child)) {
status = vfs_rmdir(&nop_mnt_idmap, d_inode(parent), child);
if (status)
printk("failed to remove client recovery directory %pd\n",
child);
- dput(child);
+ end_dirop(child);
}
- inode_unlock(d_inode(parent));
out_free:
kfree(name.data);
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 5c809cbc05fe..5bdd068dbdd7 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -2013,7 +2013,7 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
{
struct dentry *dentry, *rdentry;
struct inode *dirp;
- struct inode *rinode;
+ struct inode *rinode = NULL;
__be32 err;
int host_err;
@@ -2032,24 +2032,21 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
dentry = fhp->fh_dentry;
dirp = d_inode(dentry);
- inode_lock_nested(dirp, I_MUTEX_PARENT);
- rdentry = lookup_one(&nop_mnt_idmap, &QSTR_LEN(fname, flen), dentry);
+ rdentry = start_removing(&nop_mnt_idmap, dentry, &QSTR_LEN(fname, flen));
+
host_err = PTR_ERR(rdentry);
if (IS_ERR(rdentry))
- goto out_unlock;
+ goto out_drop_write;
- if (d_really_is_negative(rdentry)) {
- dput(rdentry);
- host_err = -ENOENT;
- goto out_unlock;
- }
- rinode = d_inode(rdentry);
err = fh_fill_pre_attrs(fhp);
if (err != nfs_ok)
goto out_unlock;
+ rinode = d_inode(rdentry);
+ /* Prevent truncation until after locks dropped */
ihold(rinode);
+
if (!type)
type = d_inode(rdentry)->i_mode & S_IFMT;
@@ -2071,10 +2068,10 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
}
fh_fill_post_attrs(fhp);
- inode_unlock(dirp);
- if (!host_err)
+out_unlock:
+ end_dirop(rdentry);
+ if (!err && !host_err)
host_err = commit_metadata(fhp);
- dput(rdentry);
iput(rinode); /* truncate the inode here */
out_drop_write:
@@ -2092,9 +2089,6 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
}
out:
return err != nfs_ok ? err : nfserrno(host_err);
-out_unlock:
- inode_unlock(dirp);
- goto out_drop_write;
}
/*
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 7371f586e318..5feb92b84d84 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -83,6 +83,8 @@ struct dentry *lookup_one_positive_unlocked(struct mnt_idmap *idmap,
struct dentry *start_creating(struct mnt_idmap *idmap, struct dentry *parent,
struct qstr *name);
+struct dentry *start_removing(struct mnt_idmap *idmap, struct dentry *parent,
+ struct qstr *name);
void end_dirop(struct dentry *de);
void end_dirop_mkdir(struct dentry *de, struct dentry *parent);
--
2.50.0.107.gf914562f5916.dirty
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