Andreas Rohner 56d7acc792 nilfs2: fix data loss with mmap() ... This bug leads to reproducible silent data loss, despite the use of msync(), sync() and a clean unmount of the file system. It is easily reproducible with the following script: ----------------[BEGIN SCRIPT]-------------------- mkfs.nilfs2 -f /dev/sdb mount /dev/sdb /mnt dd if=/dev/zero bs=1M count=30 of=/mnt/testfile umount /mnt mount /dev/sdb /mnt CHECKSUM_BEFORE="$(md5sum /mnt/testfile)" /root/mmaptest/mmaptest /mnt/testfile 30 10 5 sync CHECKSUM_AFTER="$(md5sum /mnt/testfile)" umount /mnt mount /dev/sdb /mnt CHECKSUM_AFTER_REMOUNT="$(md5sum /mnt/testfile)" umount /mnt echo "BEFORE MMAP:\t$CHECKSUM_BEFORE" echo "AFTER MMAP:\t$CHECKSUM_AFTER" echo "AFTER REMOUNT:\t$CHECKSUM_AFTER_REMOUNT" ----------------[END SCRIPT]-------------------- The mmaptest tool looks something like this (very simplified, with error checking removed): ----------------[BEGIN mmaptest]-------------------- data = mmap(NULL, file_size - file_offset, PROT_READ | PROT_WRITE, MAP_SHARED, fd, file_offset); for (i = 0; i < write_count; ++i) { memcpy(data + i * 4096, buf, sizeof(buf)); msync(data, file_size - file_offset, MS_SYNC)) } ----------------[END mmaptest]-------------------- The output of the script looks something like this: BEFORE MMAP: 281ed1d5ae50e8419f9b978aab16de83 /mnt/testfile AFTER MMAP: 6604a1c31f10780331a6850371b3a313 /mnt/testfile AFTER REMOUNT: 281ed1d5ae50e8419f9b978aab16de83 /mnt/testfile So it is clear, that the changes done using mmap() do not survive a remount. This can be reproduced a 100% of the time. The problem was introduced in commit 136e8770cd ("nilfs2: fix issue of nilfs_set_page_dirty() for page at EOF boundary"). If the page was read with mpage_readpage() or mpage_readpages() for example, then it has no buffers attached to it. In that case page_has_buffers(page) in nilfs_set_page_dirty() will be false. Therefore nilfs_set_file_dirty() is never called and the pages are never collected and never written to disk. This patch fixes the problem by also calling nilfs_set_file_dirty() if the page has no buffers attached to it. [akpm@linux-foundation.org: s/PAGE_SHIFT/PAGE_CACHE_SHIFT/] Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net> Tested-by: Andreas Rohner <andreas.rohner@gmx.net> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2014-09-26 08:10:34 -07:00
..
alloc.c
alloc.h
bmap.c
bmap.h
btnode.c
btnode.h
btree.c
btree.h
cpfile.c	nilfs2: verify metadata sizes read from disk	2014-04-03 16:21:26 -07:00
cpfile.h
dat.c	nilfs2: verify metadata sizes read from disk	2014-04-03 16:21:26 -07:00
dat.h
dir.c
direct.c
direct.h
export.h
file.c	write_iter variants of {__,}generic_file_aio_write()	2014-05-06 17:38:00 -04:00
gcinode.c
ifile.c
ifile.h
inode.c	nilfs2: fix data loss with mmap()	2014-09-26 08:10:34 -07:00
ioctl.c	nilfs2: add FITRIM ioctl support for nilfs2	2014-04-03 16:21:26 -07:00
Kconfig
Makefile	nilfs2: integrate sysfs support into driver	2014-08-08 15:57:21 -07:00
mdt.c
mdt.h
namei.c
nilfs.h	nilfs2: integrate sysfs support into driver	2014-08-08 15:57:21 -07:00
page.c
page.h
recovery.c
segbuf.c
segbuf.h
segment.c
segment.h
sufile.c	nilfs2: verify metadata sizes read from disk	2014-04-03 16:21:26 -07:00
sufile.h	nilfs2: add nilfs_sufile_trim_fs to trim clean segs	2014-04-03 16:21:25 -07:00
super.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2014-08-11 11:44:11 -07:00
sysfs.c	nilfs2: integrate sysfs support into driver	2014-08-08 15:57:21 -07:00
sysfs.h	nilfs2: add /sys/fs/nilfs2/<device>/mounted_snapshots/<snapshot> group	2014-08-08 15:57:21 -07:00
the_nilfs.c	nilfs2: integrate sysfs support into driver	2014-08-08 15:57:21 -07:00
the_nilfs.h	nilfs2: add /sys/fs/nilfs2/<device>/mounted_snapshots/<snapshot> group	2014-08-08 15:57:21 -07:00