[PATCH 5.15 021/136] btrfs: put initial index value of a directory in a constant

Greg Kroah-Hartman
2022-08-29T11:03:05Z

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 528ee697126fddaff448897c2d649bd756153c79 ]

At btrfs_set_inode_index_count() we refer twice to the number 2 as the
initial index value for a directory (when it's empty), with a proper
comment explaining the reason for that value. In the next patch I'll
have to use that magic value in the directory logging code, so put
the value in a #define at btrfs_inode.h, to avoid hardcoding the
magic value again at tree-log.c.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/btrfs_inode.h | 12 ++++++++++--
fs/btrfs/inode.c | 10 ++--------
2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 76ee1452c57ba..37ceea85b871c 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -13,6 +13,13 @@
#include "ordered-data.h"
#include "delayed-inode.h"

+/*
+ * Since we search a directory based on f_pos (struct dir_context::pos) we have
+ * to start at 2 since '.' and '..' have f_pos of 0 and 1 respectively, so
+ * everybody else has to start at 2 (see btrfs_real_readdir() and dir_emit_dots()).
+ */
+#define BTRFS_DIR_START_INDEX 2
+
/*
* ordered_data_close is set by truncate when a file that used
* to have good data has been truncated to zero. When it is set
@@ -164,8 +171,9 @@ struct btrfs_inode {
u64 disk_i_size;

/*
- * if this is a directory then index_cnt is the counter for the index
- * number for new files that are created
+ * If this is a directory then index_cnt is the counter for the index
+ * number for new files that are created. For an empty directory, this
+ * must be initialized to BTRFS_DIR_START_INDEX.
*/
u64 index_cnt;

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ac6ba984973c0..26a4acb856a38 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6396,14 +6396,8 @@ static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
goto out;
ret = 0;

- /*
- * MAGIC NUMBER EXPLANATION:
- * since we search a directory based on f_pos we have to start at 2
- * since '.' and '..' have f_pos of 0 and 1 respectively, so everybody
- * else has to start at 2
- */
if (path->slots[0] == 0) {
- inode->index_cnt = 2;
+ inode->index_cnt = BTRFS_DIR_START_INDEX;
goto out;
}

@@ -6414,7 +6408,7 @@ static int btrfs_set_inode_index_count(struct btrfs_inode *inode)

if (found_key.objectid != btrfs_ino(inode) ||
found_key.type != BTRFS_DIR_INDEX_KEY) {
- inode->index_cnt = 2;
+ inode->index_cnt = BTRFS_DIR_START_INDEX;
goto out;
}

--
2.35.1