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-rw-r--r--fs/ext4/ext4.h3
-rw-r--r--fs/ext4/namei.c21
2 files changed, 14 insertions, 10 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2d6d4c952492..d50229e92c55 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2020,7 +2020,8 @@ static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)
#define is_dx(dir) (ext4_has_feature_dir_index((dir)->i_sb) && \
ext4_test_inode_flag((dir), EXT4_INODE_INDEX))
-#define EXT4_DIR_LINK_MAX(dir) (!is_dx(dir) && (dir)->i_nlink >= EXT4_LINK_MAX)
+#define EXT4_DIR_LINK_MAX(dir) unlikely((dir)->i_nlink >= EXT4_LINK_MAX && \
+ !(ext4_has_feature_dir_nlink((dir)->i_sb) && is_dx(dir)))
#define EXT4_DIR_LINK_EMPTY(dir) ((dir)->i_nlink == 2 || (dir)->i_nlink == 1)
/* Legal values for the dx_root hash_version field: */
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 13f0cadb1238..cc986b824181 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2395,19 +2395,22 @@ out:
}
/*
- * DIR_NLINK feature is set if 1) nlinks > EXT4_LINK_MAX or 2) nlinks == 2,
- * since this indicates that nlinks count was previously 1.
+ * Set directory link count to 1 if nlinks > EXT4_LINK_MAX, or if nlinks == 2
+ * since this indicates that nlinks count was previously 1 to avoid overflowing
+ * the 16-bit i_links_count field on disk. Directories with i_nlink == 1 mean
+ * that subdirectory link counts are not being maintained accurately.
+ *
+ * The caller has already checked for i_nlink overflow in case the DIR_LINK
+ * feature is not enabled and returned -EMLINK. The is_dx() check is a proxy
+ * for checking S_ISDIR(inode) (since the INODE_INDEX feature will not be set
+ * on regular files) and to avoid creating huge/slow non-HTREE directories.
*/
static void ext4_inc_count(handle_t *handle, struct inode *inode)
{
inc_nlink(inode);
- if (is_dx(inode) && inode->i_nlink > 1) {
- /* limit is 16-bit i_links_count */
- if (inode->i_nlink >= EXT4_LINK_MAX || inode->i_nlink == 2) {
- set_nlink(inode, 1);
- ext4_set_feature_dir_nlink(inode->i_sb);
- }
- }
+ if (is_dx(inode) &&
+ (inode->i_nlink > EXT4_LINK_MAX || inode->i_nlink == 2))
+ set_nlink(inode, 1);
}
/*