Btrfs: don't insert useless holes when punching beyond the inode's size (12870f1c) · Commits · 戴 / test

If we punch beyond the size of an inode, we'll correctly remove any prealloc extents, but we'll also insert file extent items representing holes (disk bytenr == 0) that start with a key offset that lies beyond the inode's size and are not contiguous with the last file extent item. Example: $XFS_IO_PROG -f -c "truncate 118811" $SCRATCH_MNT/foo $XFS_IO_PROG -c "fpunch 582007 864596" $SCRATCH_MNT/foo $XFS_IO_PROG -c "pwrite -S 0x0d -b 39987 92267 39987" $SCRATCH_MNT/foo btrfs-debug-tree output: item 4 key (257 INODE_ITEM 0) itemoff 15885 itemsize 160 inode generation 6 transid 6 size 132254 block group 0 mode 100600 links 1 item 5 key (257 INODE_REF 256) itemoff 15872 itemsize 13 inode ref index 2 namelen 3 name: foo item 6 key (257 EXTENT_DATA 0) itemoff 15819 itemsize 53 extent data disk byte 0 nr 0 gen 6 extent data offset 0 nr 90112 ram 122880 extent compression 0 item 7 key (257 EXTENT_DATA 90112) itemoff 15766 itemsize 53 extent data disk byte 12845056 nr 4096 gen 6 extent data offset 0 nr 45056 ram 45056 extent compression 2 item 8 key (257 EXTENT_DATA 585728) itemoff 15713 itemsize 53 extent data disk byte 0 nr 0 gen 6 extent data offset 0 nr 860160 ram 860160 extent compression 0 The last extent item, which represents a hole, is useless as it lies beyond the inode's size. Signed-off-by:

Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by:

Josef Bacik <jbacik@fb.com>

fs/btrfs/file.c

+17 −11

Original line number	Diff line number	Diff line
		@@ -2168,6 +2168,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
		bool same_page = ((offset >> PAGE_CACHE_SHIFT) ==
		((offset + len - 1) >> PAGE_CACHE_SHIFT));
		bool no_holes = btrfs_fs_incompat(root->fs_info, NO_HOLES);
		u64 ino_size = round_up(inode->i_size, PAGE_CACHE_SIZE);

		ret = btrfs_wait_ordered_range(inode, offset, len);
		if (ret)
		@@ -2183,14 +2184,14 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
		* entire page.
		*/
		if (same_page && len < PAGE_CACHE_SIZE) {
		if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE))
		if (offset < ino_size)
		ret = btrfs_truncate_page(inode, offset, len, 0);
		mutex_unlock(&inode->i_mutex);
		return ret;
		}

		/* zero back part of the first page */
		if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
		if (offset < ino_size) {
		ret = btrfs_truncate_page(inode, offset, 0, 0);
		if (ret) {
		mutex_unlock(&inode->i_mutex);
		@@ -2199,7 +2200,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
		}

		/* zero the front end of the last page */
		if (offset + len < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
		if (offset + len < ino_size) {
		ret = btrfs_truncate_page(inode, offset + len, 0, 1);
		if (ret) {
		mutex_unlock(&inode->i_mutex);
		@@ -2288,11 +2289,14 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)

		trans->block_rsv = &root->fs_info->trans_block_rsv;

		ret = fill_holes(trans, inode, path, cur_offset, drop_end);
		if (cur_offset < ino_size) {
		ret = fill_holes(trans, inode, path, cur_offset,
		drop_end);
		if (ret) {
		err = ret;
		break;
		}
		}

		cur_offset = drop_end;

		@@ -2324,11 +2328,13 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
		}

		trans->block_rsv = &root->fs_info->trans_block_rsv;
		if (cur_offset < ino_size) {
		ret = fill_holes(trans, inode, path, cur_offset, drop_end);
		if (ret) {
		err = ret;
		goto out_trans;
		}
		}

		out_trans:
		if (!trans)

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