[PATCH 09/11] fs/ntfs3: take ni_lock() once in ntfs_readdir()

[Konstantin Komarov]

ntfs_readdir() took ni_lock() to load subrecords, dropped it, and then
took it again for the index walk. The double-checked pattern around
ni_load_all_mi() and the separate out_unlock label exist only because
of that split.

Take the lock once for the whole function and drop the second
acquisition, the inner re-check and the duplicate error label.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
---
 fs/ntfs3/dir.c | 38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/fs/ntfs3/dir.c b/fs/ntfs3/dir.c
index 328c9a29df89..0998c98eb49c 100644
--- a/fs/ntfs3/dir.c
+++ b/fs/ntfs3/dir.c
@@ -519,34 +519,29 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
 	if (!name)
 		return -ENOMEM;
 
+	/*
+	 * Keep directory metadata stable for the whole walk. Loading subrecords
+	 * once is not enough if concurrent writeback can still compact ATTR_LIST
+	 * entries and free the record that ntfs_read_hdr() is currently walking.
+	 */
+	ni_lock(ni);
+
 	if (!ni->mi_loaded && ni->attr_list.size) {
 		/*
 		 * Directory inode is locked for read.
 		 * Load all subrecords to avoid 'write' access to 'ni' during
 		 * directory reading.
 		 */
-		ni_lock(ni);
-		if (!ni->mi_loaded && ni->attr_list.size) {
-			err = ni_load_all_mi(ni);
-			if (!err)
-				ni->mi_loaded = true;
-		}
-		ni_unlock(ni);
+		err = ni_load_all_mi(ni);
 		if (err)
 			goto out;
+		ni->mi_loaded = true;
 	}
 
-	/*
-	 * Keep directory metadata stable for the whole walk. Loading subrecords
-	 * once is not enough if concurrent writeback can still compact ATTR_LIST
-	 * entries and free the record that ntfs_read_hdr() is currently walking.
-	 */
-	ni_lock(ni);
-
 	root = indx_get_root(&ni->dir, ni, NULL, NULL);
 	if (!root) {
 		err = -EINVAL;
-		goto out_unlock;
+		goto out;
 	}
 
 	if (pos >= sbi->record_size) {
@@ -557,7 +552,7 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
 		 */
 		err = ntfs_read_hdr(sbi, ni, &root->ihdr, 0, pos, name, ctx);
 		if (err)
-			goto out_unlock;
+			goto out;
 		bit = 0;
 	}
 
@@ -568,7 +563,7 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
 		/* Get the next used index. */
 		err = indx_used_bit(&ni->dir, ni, &bit);
 		if (err)
-			goto out_unlock;
+			goto out;
 
 		if (bit == MINUS_ONE_T) {
 			/* no more used indexes. end of dir. */
@@ -578,13 +573,13 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
 		if (bit >= max_bit) {
 			/* Corrupted directory. */
 			err = -EINVAL;
-			goto out_unlock;
+			goto out;
 		}
 
 		err = indx_read_ra(&ni->dir, ni, bit << ni->dir.idx2vbn_bits,
 				   &node, &file->f_ra);
 		if (err)
-			goto out_unlock;
+			goto out;
 
 		/*
 		 * Add each name from index in 'ctx'.
@@ -593,13 +588,12 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
 				    ((u64)bit << index_bits) + sbi->record_size,
 				    pos, name, ctx);
 		if (err)
-			goto out_unlock;
+			goto out;
 	}
 
-out_unlock:
+out:
 	ni_unlock(ni);
 
-out:
 	kfree(name);
 	put_indx_node(node);
 
-- 
2.43.0