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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     viro@zeniv.linux.org.uk, tytso@mit.edu, jaegeuk@kernel.org
Cc:     ebiggers@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        kernel@collabora.com
Subject: [PATCH RFC 6/7] ext4: Enable negative dentries on case-insensitive lookup
Date:   Wed,  1 Jun 2022 16:44:36 -0400
Message-Id: <20220601204437.676872-7-krisman@collabora.com>
In-Reply-To: <20220601204437.676872-1-krisman@collabora.com>
References: <20220601204437.676872-1-krisman@collabora.com>
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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>
---
 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 767b4bfe39c3..783ba0b186c1 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1800,16 +1800,9 @@ 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
+	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
+		d_set_casefold_lookup(dentry);
+
 	return d_splice_alias(inode, dentry);
 }
 
@@ -3126,17 +3119,6 @@ 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)
@@ -3231,16 +3213,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	retval = __ext4_unlink(handle, dir, &dentry->d_name, d_inode(dentry));
 	if (!retval)
 		ext4_fc_track_unlink(handle, 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
+
 	if (handle)
 		ext4_journal_stop(handle);
 
-- 
2.36.1