f2fs: don't GC or take an fs_lock from f2fs_initxattrs()

f2fs_initxattrs() is called internally from within F2FS and should
not call functions that are used by VFS handlers.  This avoids
certain deadlocks:

- vfs_create()
 - f2fs_create() <-- takes an fs_lock
  - f2fs_add_link()
   - __f2fs_add_link()
    - init_inode_metadata()
     - f2fs_init_security()
      - security_inode_init_security()
       - f2fs_initxattrs()
        - f2fs_setxattr() <-- also takes an fs_lock

If the caller happens to grab the same fs_lock from the pool in both
places, they will deadlock.  There are also deadlocks involving
multiple threads and mutexes:

- f2fs_write_begin()
 - f2fs_balance_fs() <-- takes gc_mutex
  - f2fs_gc()
   - write_checkpoint()
    - block_operations()
     - mutex_lock_all() <-- blocks trying to grab all fs_locks

- f2fs_mkdir() <-- takes an fs_lock
 - __f2fs_add_link()
  - f2fs_init_security()
   - security_inode_init_security()
    - f2fs_initxattrs()
     - f2fs_setxattr()
      - f2fs_balance_fs() <-- blocks trying to take gc_mutex

Signed-off-by: Russ Knize <Russ.Knize@motorola.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 25 insertions, 10 deletions

diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index 1ac8a5f6e380..3d900ea34e47 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -154,6 +154,9 @@ static int f2fs_xattr_advise_set(struct dentry *dentry, const char *name,
 }
 
 #ifdef CONFIG_F2FS_FS_SECURITY
+static int __f2fs_setxattr(struct inode *inode, int name_index,
+                        const char *name, const void *value, size_t value_len,
+                        struct page *ipage);
 static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
                 void *page)
 {
@@ -161,7 +164,7 @@ static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
         int err = 0;
 
         for (xattr = xattr_array; xattr->name != NULL; xattr++) {
-                err = f2fs_setxattr(inode, F2FS_XATTR_INDEX_SECURITY,
+                err = __f2fs_setxattr(inode, F2FS_XATTR_INDEX_SECURITY,
                                 xattr->name, xattr->value,
                                 xattr->value_len, (struct page *)page);
                 if (err < 0)
@@ -469,16 +472,15 @@ cleanup:
         return error;
 }
 
-int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
-                        const void *value, size_t value_len, struct page *ipage)
+static int __f2fs_setxattr(struct inode *inode, int name_index,
+                        const char *name, const void *value, size_t value_len,
+                        struct page *ipage)
 {
-        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
         struct f2fs_inode_info *fi = F2FS_I(inode);
         struct f2fs_xattr_entry *here, *last;
         void *base_addr;
         int found, newsize;
         size_t name_len;
-        int ilock;
         __u32 new_hsize;
         int error = -ENOMEM;
 
@@ -493,10 +495,6 @@ int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
         if (name_len > F2FS_NAME_LEN || value_len > MAX_VALUE_LEN(inode))
                 return -ERANGE;
 
-        f2fs_balance_fs(sbi);
-
-        ilock = mutex_lock_op(sbi);
-
         base_addr = read_all_xattrs(inode, ipage);
         if (!base_addr)
                 goto exit;
@@ -578,7 +576,24 @@ int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
         else
                 update_inode_page(inode);
 exit:
-        mutex_unlock_op(sbi, ilock);
         kzfree(base_addr);
         return error;
 }
+
+int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
+                        const void *value, size_t value_len, struct page *ipage)
+{
+        struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+        int ilock;
+        int err;
+
+        f2fs_balance_fs(sbi);
+
+        ilock = mutex_lock_op(sbi);
+
+        err = __f2fs_setxattr(inode, name_index, name, value, value_len, ipage);
+
+        mutex_unlock_op(sbi, ilock);
+
+        return err;
+}