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authorAnton Altaparmakov <aia21@cantab.net>2005-09-08 21:25:48 +0100
committerAnton Altaparmakov <aia21@cantab.net>2005-09-08 21:25:48 +0100
commit8dcdebafb848415eae25924b00c4f0b9ec907da0 (patch)
tree5e7289dca23148d6b157817c6272c0fc3460f449 /fs/ntfs/aops.c
parent67bb103725e4cde322cb4ddb160a12933c5c7072 (diff)
downloadlinux-linaro-8dcdebafb848415eae25924b00c4f0b9ec907da0.tar.gz
NTFS: Make ntfs_write_block() not instantiate sparse blocks if they are zero.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Diffstat (limited to 'fs/ntfs/aops.c')
-rw-r--r--fs/ntfs/aops.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 78adad7a988..f3ad36d8b8c 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -670,6 +670,27 @@ lock_retry_remap:
}
/* It is a hole, need to instantiate it. */
if (lcn == LCN_HOLE) {
+ u8 *kaddr;
+ unsigned long *bpos, *bend;
+
+ /* Check if the buffer is zero. */
+ kaddr = kmap_atomic(page, KM_USER0);
+ bpos = (unsigned long *)(kaddr + bh_offset(bh));
+ bend = (unsigned long *)((u8*)bpos + blocksize);
+ do {
+ if (unlikely(*bpos))
+ break;
+ } while (likely(++bpos < bend));
+ kunmap_atomic(kaddr, KM_USER0);
+ if (bpos == bend) {
+ /*
+ * Buffer is zero and sparse, no need to write
+ * it.
+ */
+ bh->b_blocknr = -1;
+ clear_buffer_dirty(bh);
+ continue;
+ }
// TODO: Instantiate the hole.
// clear_buffer_new(bh);
// unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);