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Commit 5a73f252 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: allocate blocks for pinned file 



This patch allows fallocate to allocate physical blocks for pinned file.

Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent fd8ff0c6

Documentation/filesystems/f2fs.txt

+25 −0
Original line number Diff line number Diff line
@@ -744,3 +744,28 @@ algorithm. 
In order to identify whether the data in the victim segment are valid or not,

F2FS manages a bitmap. Each bit represents the validity of a block, and the

bitmap is composed of a bit stream covering whole blocks in main area.



Fallocate(2) Policy

-------------------



The default policy follows the below posix rule.



Allocating disk space

    The default operation (i.e., mode is zero) of fallocate() allocates

    the disk space within the range specified by offset and len.  The

    file size (as reported by stat(2)) will be changed if offset+len is

    greater than the file size.  Any subregion within the range specified

    by offset and len that did not contain data before the call will be

    initialized to zero.  This default behavior closely resembles the

    behavior of the posix_fallocate(3) library function, and is intended

    as a method of optimally implementing that function.



However, once F2FS receives ioctl(fd, F2FS_IOC_SET_PIN_FILE) in prior to

fallocate(fd, DEFAULT_MODE), it allocates on-disk blocks addressess having

zero or random data, which is useful to the below scenario where:

 1. create(fd)

 2. ioctl(fd, F2FS_IOC_SET_PIN_FILE)

 3. fallocate(fd, 0, 0, size)

 4. address = fibmap(fd, offset)

 5. open(blkdev)

 6. write(blkdev, address)

fs/f2fs/file.c

+6 −1
Original line number Diff line number Diff line
@@ -1531,7 +1531,12 @@ static int expand_inode_data(struct inode *inode, loff_t offset, 
	if (off_end)

		map.m_len++;



	err = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_AIO);

	if (f2fs_is_pinned_file(inode))

		map.m_seg_type = CURSEG_COLD_DATA;



	err = f2fs_map_blocks(inode, &map, 1, (f2fs_is_pinned_file(inode) ?

						F2FS_GET_BLOCK_PRE_DIO :

						F2FS_GET_BLOCK_PRE_AIO));

	if (err) {

		pgoff_t last_off;