ext4: move dcache manipulation out of __ext4_link()

__ext4_link() has two callers.

- ext4_link() calls it during normal handling of the link() system
  call or similar
- ext4_fc_replay_link_internal() calls it when replaying the journal
  at mount time.

The former needs changes to dcache - instantiating the dentry to the
inode on success.  The latter doesn't need or want any dcache
manipulation.

So move the manipulation out of __ext4_link() and do it in ext4_link()
only.

This requires:
 - passing the qname from the dentry explicitly to __ext4_link.
   The parent dir is already passed.  The dentry is still passed
   in the ext4_link() case purely for use by ext4_fc_track_link().
 - passing the inode separately to ext4_fc_track_link() as the
   dentry will not be instantiated yet.
 - using __ext4_add_entry() in ext4_link, which doesn't need a dentry.
 - moving ihold(), d_instantiate(), drop_nlink() and iput() calls out
   of __ext4_link() into ext4_link().

Note that ext4_inc_count() and drop_nlink() remain in __ext4_link()
as both callers need them and they are not related to the dentry.

This substantially simplifies ext4_fc_replay_link_internal(), and
removes a use of d_alloc() which, it is planned, will be removed.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20260320000838.3797494-4-neilb@ownmail.net
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 7d2564f642267c2ff1b8c94870e717eddc08b46d..58fd1ea1e5017f2c30a03ff34ebb62d5c6c5b173 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2971,7 +2971,8 @@ void __ext4_fc_track_unlink(handle_t *handle, struct inode *inode,
 void __ext4_fc_track_link(handle_t *handle, struct inode *inode,
        struct dentry *dentry);
 void ext4_fc_track_unlink(handle_t *handle, struct dentry *dentry);
-void ext4_fc_track_link(handle_t *handle, struct dentry *dentry);
+void ext4_fc_track_link(handle_t *handle, struct inode *inode,
+                       struct dentry *dentry);
 void __ext4_fc_track_create(handle_t *handle, struct inode *inode,
                            struct dentry *dentry);
 void ext4_fc_track_create(handle_t *handle, struct dentry *dentry);
@@ -3716,7 +3717,7 @@ extern int ext4_handle_dirty_dirblock(handle_t *handle, struct inode *inode,
 extern int __ext4_unlink(struct inode *dir, const struct qstr *d_name,
                         struct inode *inode, struct dentry *dentry);
 extern int __ext4_link(struct inode *dir, struct inode *inode,
-                      struct dentry *dentry);
+                      const struct qstr *d_name, struct dentry *dentry);
 
 #define S_SHIFT 12
 static const unsigned char ext4_type_by_mode[(S_IFMT >> S_SHIFT) + 1] = {

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index e58484d69d8e67f1056efcdf4b23cfc1bc444ed3..7bcba3cb550fe2199f6f168f4d2cca87f79302a6 100644 (file)
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -497,10 +497,9 @@ void __ext4_fc_track_link(handle_t *handle,
        trace_ext4_fc_track_link(handle, inode, dentry, ret);
 }
 
-void ext4_fc_track_link(handle_t *handle, struct dentry *dentry)
+void ext4_fc_track_link(handle_t *handle, struct inode *inode,
+                       struct dentry *dentry)
 {
-       struct inode *inode = d_inode(dentry);
-
        if (ext4_fc_eligible(inode->i_sb))
                __ext4_fc_track_link(handle, inode, dentry);
 }
@@ -1431,7 +1430,6 @@ static int ext4_fc_replay_link_internal(struct super_block *sb,
                                struct inode *inode)
 {
        struct inode *dir = NULL;
-       struct dentry *dentry_dir = NULL, *dentry_inode = NULL;
        struct qstr qstr_dname = QSTR_INIT(darg->dname, darg->dname_len);
        int ret = 0;
 
@@ -1442,21 +1440,7 @@ static int ext4_fc_replay_link_internal(struct super_block *sb,
                goto out;
        }
 
-       dentry_dir = d_obtain_alias(dir);
-       if (IS_ERR(dentry_dir)) {
-               ext4_debug("Failed to obtain dentry");
-               dentry_dir = NULL;
-               goto out;
-       }
-
-       dentry_inode = d_alloc(dentry_dir, &qstr_dname);
-       if (!dentry_inode) {
-               ext4_debug("Inode dentry not created.");
-               ret = -ENOMEM;
-               goto out;
-       }
-
-       ret = __ext4_link(dir, inode, dentry_inode);
+       ret = __ext4_link(dir, inode, &qstr_dname, NULL);
        /*
         * It's possible that link already existed since data blocks
         * for the dir in question got persisted before we crashed OR
@@ -1470,16 +1454,8 @@ static int ext4_fc_replay_link_internal(struct super_block *sb,
 
        ret = 0;
 out:
-       if (dentry_dir) {
-               d_drop(dentry_dir);
-               dput(dentry_dir);
-       } else if (dir) {
+       if (dir)
                iput(dir);
-       }
-       if (dentry_inode) {
-               d_drop(dentry_inode);
-               dput(dentry_inode);
-       }
 
        return ret;
 }

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index ba3d85a9c12069d76e5501343e80d7c904c9fab1..0b8e25198b177bf0c6f1f6a15da587515abed603 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3452,7 +3452,8 @@ out_retry:
        return err;
 }
 
-int __ext4_link(struct inode *dir, struct inode *inode, struct dentry *dentry)
+int __ext4_link(struct inode *dir, struct inode *inode,
+               const struct qstr *d_name, struct dentry *dentry)
 {
        handle_t *handle;
        int err, retries = 0;
@@ -3468,9 +3469,8 @@ retry:
 
        inode_set_ctime_current(inode);
        ext4_inc_count(inode);
-       ihold(inode);
 
-       err = ext4_add_entry(handle, dentry, inode);
+       err = __ext4_add_entry(handle, dir, d_name, inode);
        if (!err) {
                err = ext4_mark_inode_dirty(handle, inode);
                /* this can happen only for tmpfile being
@@ -3478,11 +3478,10 @@ retry:
                 */
                if (inode->i_nlink == 1)
                        ext4_orphan_del(handle, inode);
-               d_instantiate(dentry, inode);
-               ext4_fc_track_link(handle, dentry);
+               if (dentry)
+                       ext4_fc_track_link(handle, inode, dentry);
        } else {
                drop_nlink(inode);
-               iput(inode);
        }
        ext4_journal_stop(handle);
        if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
@@ -3511,9 +3510,13 @@ static int ext4_link(struct dentry *old_dentry,
        err = dquot_initialize(dir);
        if (err)
                return err;
-       return __ext4_link(dir, inode, dentry);
+       err = __ext4_link(dir, inode, &dentry->d_name, dentry);
+       if (!err) {
+               ihold(inode);
+               d_instantiate(dentry, inode);
+       }
+       return err;
 }
-
 /*
  * Try to find buffer head where contains the parent block.
  * It should be the inode block if it is inlined or the 1st block