[PATCH 4.16 180/272] f2fs: fix to set KEEP_SIZE bit in f2fs_zero_range

Greg Kroah-Hartman
2018-05-28T11:12:18Z

From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 17cd07ae95073c298af92c1ba14ac58ce84de33b ]

As Jayashree Mohan reported:

A simple workload to reproduce this would be :
1. create foo
2. Write (8K - 16K) // foo size = 16K now
3. fsync()
4. falloc zero_range , keep_size (4202496 - 4210688) // foo size must be 16K
5. fdatasync()
Crash now

On recovery, we see that the file size is 4210688 and not 16K, which
violates the semantics of keep_size flag. We have a test case to
reproduce this using CrashMonkey on 4.15 kernel. Try this out by
simply running :
./c_harness -f /dev/sda -d /dev/cow_ram0 -t f2fs -e 102400 -P -v
tests/generic_468_zero.so

The root cause is that we miss to set KEEP_SIZE bit correctly in zero_range
when zeroing block cross EOF with FALLOC_FL_KEEP_SIZE, let's fix this
missing case.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/file.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1348,8 +1348,12 @@ static int f2fs_zero_range(struct inode
}

out:
- if (!(mode & FALLOC_FL_KEEP_SIZE) && i_size_read(inode) < new_size)
- f2fs_i_size_write(inode, new_size);
+ if (new_size > i_size_read(inode)) {
+ if (mode & FALLOC_FL_KEEP_SIZE)
+ file_set_keep_isize(inode);
+ else
+ f2fs_i_size_write(inode, new_size);
+ }
out_sem:
up_write(&F2FS_I(inode)->i_mmap_sem);