Merge remote branch 'anholt/drm-intel-next' into drm-next

* anholt/drm-intel-next: (515 commits)
  drm/i915: Fix out of tree builds
  drm/i915: move fence lru to struct drm_i915_fence_reg
  drm/i915: don't allow tiling changes on pinned buffers v2
  drm/i915: Be extra careful about A/D matching for multifunction SDVO
  drm/i915: Fix DDC bus selection for multifunction SDVO
  drm/i915: cleanup mode setting before unmapping registers
  drm/i915: Make fbc control wrapper functions
  drm/i915: Wait for the GPU whilst shrinking, if truly desperate.
  drm/i915: Use spatio-temporal dithering on PCH
  [MTD] Remove zero-length files mtdbdi.c and internal.ho
  pata_pcmcia / ide-cs: Fix bad hashes for Transcend and kingston IDs
  libata: Fix several inaccuracies in developer's guide
  slub: Fix bad boundary check in init_kmem_cache_nodes()
  raid6: fix recovery performance regression
  KEYS: call_sbin_request_key() must write lock keyrings before modifying them
  KEYS: Use RCU dereference wrappers in keyring key type code
  KEYS: find_keyring_by_name() can gain access to a freed keyring
  ALSA: hda: Fix 0 dB for Packard Bell models using Conexant CX20549 (Venice)
  ALSA: hda - Add quirk for Dell Inspiron 19T using a Conexant CX20582
  ALSA: take tu->qlock with irqs disabled
  ...

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 2a6d0193f139..6dcee88c2e5d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -406,16 +406,23 @@ static loff_t block_llseek(struct file *file, loff_t offset, int origin)
  
 int blkdev_fsync(struct file *filp, struct dentry *dentry, int datasync)
 {
-        struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+        struct inode *bd_inode = filp->f_mapping->host;
+        struct block_device *bdev = I_BDEV(bd_inode);
         int error;
 
-        error = sync_blockdev(bdev);
-        if (error)
-                return error;
-        
+        /*
+         * There is no need to serialise calls to blkdev_issue_flush with
+         * i_mutex and doing so causes performance issues with concurrent
+         * O_SYNC writers to a block device.
+         */
+        mutex_unlock(&bd_inode->i_mutex);
+
         error = blkdev_issue_flush(bdev, NULL);
         if (error == -EOPNOTSUPP)
                 error = 0;
+
+        mutex_lock(&bd_inode->i_mutex);
+
         return error;
 }
 EXPORT_SYMBOL(blkdev_fsync);