1 files changed, 34 insertions, 10 deletions

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 43e8b2c0664b..cc3f1aa1cf7b 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -231,7 +231,8 @@ static int ioctl_fiemap(struct file *filp, unsigned long arg)
 #define blk_to_logical(inode, blk) (blk << (inode)->i_blkbits)
 #define logical_to_blk(inode, offset) (offset >> (inode)->i_blkbits);
 
-/*
+/**
+ * __generic_block_fiemap - FIEMAP for block based inodes (no locking)
  * @inode - the inode to map
  * @arg - the pointer to userspace where we copy everything to
  * @get_block - the fs's get_block function
@@ -242,11 +243,15 @@ static int ioctl_fiemap(struct file *filp, unsigned long arg)
  *
  * If it is possible to have data blocks beyond a hole past @inode->i_size, then
  * please do not use this function, it will stop at the first unmapped block
- * beyond i_size
+ * beyond i_size.
+ *
+ * If you use this function directly, you need to do your own locking. Use
+ * generic_block_fiemap if you want the locking done for you.
  */
-int generic_block_fiemap(struct inode *inode,
-                         struct fiemap_extent_info *fieinfo, u64 start,
-                         u64 len, get_block_t *get_block)
+
+int __generic_block_fiemap(struct inode *inode,
+                           struct fiemap_extent_info *fieinfo, u64 start,
+                           u64 len, get_block_t *get_block)
 {
         struct buffer_head tmp;
         unsigned int start_blk;
@@ -260,9 +265,6 @@ int generic_block_fiemap(struct inode *inode,
 
         start_blk = logical_to_blk(inode, start);
 
-        /* guard against change */
-        mutex_lock(&inode->i_mutex);
-
         length = (long long)min_t(u64, len, i_size_read(inode));
         map_len = length;
 
@@ -334,14 +336,36 @@ int generic_block_fiemap(struct inode *inode,
                 cond_resched();
         } while (1);
 
-        mutex_unlock(&inode->i_mutex);
-
         /* if ret is 1 then we just hit the end of the extent array */
         if (ret == 1)
                 ret = 0;
 
         return ret;
 }
+EXPORT_SYMBOL(__generic_block_fiemap);
+
+/**
+ * generic_block_fiemap - FIEMAP for block based inodes
+ * @inode: The inode to map
+ * @fieinfo: The mapping information
+ * @start: The initial block to map
+ * @len: The length of the extect to attempt to map
+ * @get_block: The block mapping function for the fs
+ *
+ * Calls __generic_block_fiemap to map the inode, after taking
+ * the inode's mutex lock.
+ */
+
+int generic_block_fiemap(struct inode *inode,
+                         struct fiemap_extent_info *fieinfo, u64 start,
+                         u64 len, get_block_t *get_block)
+{
+        int ret;
+        mutex_lock(&inode->i_mutex);
+        ret = __generic_block_fiemap(inode, fieinfo, start, len, get_block);
+        mutex_unlock(&inode->i_mutex);
+        return ret;
+}
 EXPORT_SYMBOL(generic_block_fiemap);
 
 #endif  /*  CONFIG_BLOCK  */