2 files changed, 49 insertions, 15 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 40106b7ea4b8..da224974af78 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1629,6 +1629,35 @@ static int ext4_delete_entry (handle_t *handle,
         return -ENOENT;
 }
 
+/*
+ * DIR_NLINK feature is set if 1) nlinks > EXT4_LINK_MAX or 2) nlinks == 2,
+ * since this indicates that nlinks count was previously 1.
+ */
+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) {
+                        inode->i_nlink = 1;
+                        EXT4_SET_RO_COMPAT_FEATURE(inode->i_sb,
+                                              EXT4_FEATURE_RO_COMPAT_DIR_NLINK);
+                }
+        }
+}
+
+/*
+ * If a directory had nlink == 1, then we should let it be 1. This indicates
+ * directory has >EXT4_LINK_MAX subdirs.
+ */
+static void ext4_dec_count(handle_t *handle, struct inode *inode)
+{
+        drop_nlink(inode);
+        if (S_ISDIR(inode->i_mode) && inode->i_nlink == 0)
+                inc_nlink(inode);
+}
+
+
 static int ext4_add_nondir(handle_t *handle,
                 struct dentry *dentry, struct inode *inode)
 {
@@ -1725,7 +1754,7 @@ static int ext4_mkdir(struct inode * dir, struct dentry * dentry, int mode)
         struct ext4_dir_entry_2 * de;
         int err, retries = 0;
 
-        if (dir->i_nlink >= EXT4_LINK_MAX)
+        if (EXT4_DIR_LINK_MAX(dir))
                 return -EMLINK;
 
 retry:
@@ -1748,7 +1777,7 @@ retry:
         inode->i_size = EXT4_I(inode)->i_disksize = inode->i_sb->s_blocksize;
         dir_block = ext4_bread (handle, inode, 0, 1, &err);
         if (!dir_block) {
-                drop_nlink(inode); /* is this nlink == 0? */
+                ext4_dec_count(handle, inode); /* is this nlink == 0? */
                 ext4_mark_inode_dirty(handle, inode);
                 iput (inode);
                 goto out_stop;
@@ -1780,7 +1809,7 @@ retry:
                 iput (inode);
                 goto out_stop;
         }
-        inc_nlink(dir);
+        ext4_inc_count(handle, dir);
         ext4_update_dx_flag(dir);
         ext4_mark_inode_dirty(handle, dir);
         d_instantiate(dentry, inode);
@@ -2045,9 +2074,9 @@ static int ext4_rmdir (struct inode * dir, struct dentry *dentry)
         retval = ext4_delete_entry(handle, dir, de, bh);
         if (retval)
                 goto end_rmdir;
-        if (inode->i_nlink != 2)
+        if (!EXT4_DIR_LINK_EMPTY(inode))
                 ext4_warning (inode->i_sb, "ext4_rmdir",
-                              "empty directory has nlink!=2 (%d)",
+                              "empty directory has too many links (%d)",
                               inode->i_nlink);
         inode->i_version++;
         clear_nlink(inode);
@@ -2058,7 +2087,7 @@ static int ext4_rmdir (struct inode * dir, struct dentry *dentry)
         ext4_orphan_add(handle, inode);
         inode->i_ctime = dir->i_ctime = dir->i_mtime = ext4_current_time(inode);
         ext4_mark_inode_dirty(handle, inode);
-        drop_nlink(dir);
+        ext4_dec_count(handle, dir);
         ext4_update_dx_flag(dir);
         ext4_mark_inode_dirty(handle, dir);
 
@@ -2109,7 +2138,7 @@ static int ext4_unlink(struct inode * dir, struct dentry *dentry)
         dir->i_ctime = dir->i_mtime = ext4_current_time(dir);
         ext4_update_dx_flag(dir);
         ext4_mark_inode_dirty(handle, dir);
-        drop_nlink(inode);
+        ext4_dec_count(handle, inode);
         if (!inode->i_nlink)
                 ext4_orphan_add(handle, inode);
         inode->i_ctime = ext4_current_time(inode);
@@ -2159,7 +2188,7 @@ retry:
                 err = __page_symlink(inode, symname, l,
                                 mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
                 if (err) {
-                        drop_nlink(inode);
+                        ext4_dec_count(handle, inode);
                         ext4_mark_inode_dirty(handle, inode);
                         iput (inode);
                         goto out_stop;
@@ -2185,8 +2214,9 @@ static int ext4_link (struct dentry * old_dentry,
         struct inode *inode = old_dentry->d_inode;
         int err, retries = 0;
 
-        if (inode->i_nlink >= EXT4_LINK_MAX)
+        if (EXT4_DIR_LINK_MAX(inode))
                 return -EMLINK;
+
         /*
          * Return -ENOENT if we've raced with unlink and i_nlink is 0.  Doing
          * otherwise has the potential to corrupt the orphan inode list.
@@ -2204,7 +2234,7 @@ retry:
                 handle->h_sync = 1;
 
         inode->i_ctime = ext4_current_time(inode);
-        inc_nlink(inode);
+        ext4_inc_count(handle, inode);
         atomic_inc(&inode->i_count);
 
         err = ext4_add_nondir(handle, dentry, inode);
@@ -2337,7 +2367,7 @@ static int ext4_rename (struct inode * old_dir, struct dentry *old_dentry,
         }
 
         if (new_inode) {
-                drop_nlink(new_inode);
+                ext4_dec_count(handle, new_inode);
                 new_inode->i_ctime = ext4_current_time(new_inode);
         }
         old_dir->i_ctime = old_dir->i_mtime = ext4_current_time(old_dir);
@@ -2348,11 +2378,13 @@ static int ext4_rename (struct inode * old_dir, struct dentry *old_dentry,
                 PARENT_INO(dir_bh->b_data) = cpu_to_le32(new_dir->i_ino);
                 BUFFER_TRACE(dir_bh, "call ext4_journal_dirty_metadata");
                 ext4_journal_dirty_metadata(handle, dir_bh);
-                drop_nlink(old_dir);
+                ext4_dec_count(handle, old_dir);
                 if (new_inode) {
-                        drop_nlink(new_inode);
+                        /* checked empty_dir above, can't have another parent,
+                         * ext3_dec_count() won't work for many-linked dirs */
+                        new_inode->i_nlink = 0;
                 } else {
-                        inc_nlink(new_dir);
+                        ext4_inc_count(handle, new_dir);
                         ext4_update_dx_flag(new_dir);
                         ext4_mark_inode_dirty(handle, new_dir);
                 }
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index 52dcc24dd986..cdee7aaa57aa 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -71,7 +71,7 @@
 /*
  * Maximal count of links to a file
  */
-#define EXT4_LINK_MAX           32000
+#define EXT4_LINK_MAX           65000
 
 /*
  * Macro-instructions used to manage several block sizes
@@ -692,6 +692,7 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 #define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER     0x0001
 #define EXT4_FEATURE_RO_COMPAT_LARGE_FILE       0x0002
 #define EXT4_FEATURE_RO_COMPAT_BTREE_DIR        0x0004
+#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK        0x0020
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE      0x0040
 
 #define EXT4_FEATURE_INCOMPAT_COMPRESSION       0x0001
@@ -710,6 +711,7 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
                                          EXT4_FEATURE_INCOMPAT_64BIT)
 #define EXT4_FEATURE_RO_COMPAT_SUPP     (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                                          EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
+                                         EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
                                          EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
                                          EXT4_FEATURE_RO_COMPAT_BTREE_DIR)