[PATCH v6 8/9] ext4: Enable negative dentries on case-insensitive lookup

[Gabriel Krisman Bertazi <krisman@suse.de>]

From: Gabriel Krisman Bertazi <krisman@collabora.com>

Instead of invalidating negative dentries during case-insensitive
lookups, mark them as such and let them be added to the dcache.
d_ci_revalidate is able to properly filter them out if necessary based
on the dentry casefold flag.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v5:
  - Use IS_CASEFOLDED directly (Eric)
Changes since v4:
  - Use helper to decide if should set dentry flag.
Changes since v2:

  - Move dentry flag set closer to fscrypt code (Eric)
---
 fs/ext4/namei.c | 35 ++++-------------------------------
 1 file changed, 4 insertions(+), 31 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 0caf6c730ce3..d8a1c59eeae1 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1759,6 +1759,10 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir,
 
 	err = ext4_fname_prepare_lookup(dir, dentry, &fname);
 	generic_set_encrypted_ci_d_ops(dentry);
+
+	if (IS_CASEFOLDED(dir))
+		d_set_casefolded_name(dentry);
+
 	if (err == -ENOENT)
 		return NULL;
 	if (err)
@@ -1866,16 +1870,6 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
 		}
 	}
 
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (!inode && IS_CASEFOLDED(dir)) {
-		/* Eventually we want to call d_add_ci(dentry, NULL)
-		 * for negative dentries in the encoding case as
-		 * well.  For now, prevent the negative dentry
-		 * from being cached.
-		 */
-		return NULL;
-	}
-#endif
 	return d_splice_alias(inode, dentry);
 }
 
@@ -3206,17 +3200,6 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
 	ext4_fc_track_unlink(handle, dentry);
 	retval = ext4_mark_inode_dirty(handle, dir);
 
-#if IS_ENABLED(CONFIG_UNICODE)
-	/* VFS negative dentries are incompatible with Encoding and
-	 * Case-insensitiveness. Eventually we'll want avoid
-	 * invalidating the dentries here, alongside with returning the
-	 * negative dentries at ext4_lookup(), when it is better
-	 * supported by the VFS for the CI case.
-	 */
-	if (IS_CASEFOLDED(dir))
-		d_invalidate(dentry);
-#endif
-
 end_rmdir:
 	brelse(bh);
 	if (handle)
@@ -3317,16 +3300,6 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 		goto out_trace;
 
 	retval = __ext4_unlink(dir, &dentry->d_name, d_inode(dentry), dentry);
-#if IS_ENABLED(CONFIG_UNICODE)
-	/* VFS negative dentries are incompatible with Encoding and
-	 * Case-insensitiveness. Eventually we'll want avoid
-	 * invalidating the dentries here, alongside with returning the
-	 * negative dentries at ext4_lookup(), when it is  better
-	 * supported by the VFS for the CI case.
-	 */
-	if (IS_CASEFOLDED(dir))
-		d_invalidate(dentry);
-#endif
 
 out_trace:
 	trace_ext4_unlink_exit(dentry, retval);
-- 
2.41.0