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f2fs: allocate blocks for pinned file

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

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim 2019-06-26 18:23:05 -07:00
parent 4b56b2d6d8
commit 427cc7cb30
2 changed files with 31 additions and 1 deletions
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25
Documentation/filesystems/f2fs.txt
View file

@ -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)

7
fs/f2fs/file.c
View file

@ -1537,7 +1537,12 @@ 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;