[PATCH] ext4: fix sleep inside spinlock issue aka #14739 V2

[Dmitry Monakhov <dmonakhov@openvz.org>]

drop i_block_reservation_lock before vfs_dq_reserve_block().
this patch fix http://bugzilla.kernel.org/show_bug.cgi?id=14739

changes from previous version:
 - simplify the patch according to Jan's comments

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/ext4/inode.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 942e183..2327f7a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1851,6 +1851,7 @@ repeat:
 
 	md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
 	total = md_needed + nrblocks;
+	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 
 	/*
 	 * Make quota reservation here to prevent quota overflow
@@ -1858,12 +1859,10 @@ repeat:
 	 * time.
 	 */
 	if (vfs_dq_reserve_block(inode, total)) {
-		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 		return -EDQUOT;
 	}
 
 	if (ext4_claim_free_blocks(sbi, total)) {
-		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 		vfs_dq_release_reservation_block(inode, total);
 		if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
 			yield();
@@ -1871,10 +1870,11 @@ repeat:
 		}
 		return -ENOSPC;
 	}
+	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 	EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
 	EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;