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NTFS: Make ntfs_write_block() not instantiate sparse blocks if they are zero.

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Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
This commit is contained in:
Anton Altaparmakov 2005-09-08 21:25:48 +01:00
parent 67bb103725
commit 8dcdebafb8
2 changed files with 23 additions and 0 deletions
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2
fs/ntfs/ChangeLog
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@ -77,6 +77,8 @@ ToDo/Notes:
updating the times in the inode in ntfs_setattr(). updating the times in the inode in ntfs_setattr().
- Fixup handling of sparse, compressed, and encrypted attributes in - Fixup handling of sparse, compressed, and encrypted attributes in
fs/ntfs/inode.c::ntfs_read_locked_{,attr_,index_}inode(). fs/ntfs/inode.c::ntfs_read_locked_{,attr_,index_}inode().
- Make ntfs_write_block() not instantiate sparse blocks if they contain
only zeroes.
2.1.23 - Implement extension of resident files and make writing safe as well as 2.1.23 - Implement extension of resident files and make writing safe as well as
many bug fixes, cleanups, and enhancements... many bug fixes, cleanups, and enhancements...

21
fs/ntfs/aops.c
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@ -670,6 +670,27 @@ lock_retry_remap:
} }
/* It is a hole, need to instantiate it. */ /* It is a hole, need to instantiate it. */
if (lcn == LCN_HOLE) { 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. // TODO: Instantiate the hole.
// clear_buffer_new(bh); // clear_buffer_new(bh);
// unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); // unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);