ext4: Properly update i_disksize.

With delayed allocation we use i_data_sem to update i_disksize.  We need
to update i_disksize only if the new size specified is greater than the
current value and we need to make sure we don't race with other
i_disksize update.  With delayed allocation we will switch to the
write_begin function for non-delayed allocation if we are low on free
blocks.  This means the write_begin function for non-delayed allocation
also needs to use the same locking.

We also need to check and update i_disksize even if the new size is less
that inode.i_size because of delayed allocation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 797f0602a68f..e8758df2617b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2878,10 +2878,11 @@ static void ext4_falloc_update_inode(struct inode *inode,
          * Update only when preallocation was requested beyond
          * the file size.
          */
-        if (!(mode & FALLOC_FL_KEEP_SIZE) &&
-                                new_size > i_size_read(inode)) {
-                i_size_write(inode, new_size);
-                EXT4_I(inode)->i_disksize = new_size;
+        if (!(mode & FALLOC_FL_KEEP_SIZE)) {
+                if (new_size > i_size_read(inode))
+                        i_size_write(inode, new_size);
+                if (new_size > EXT4_I(inode)->i_disksize)
+                        ext4_update_i_disksize(inode, new_size);
         }
 
 }