Messages in this thread | | | Subject | Re: [PATCH v3] f2fs: fix to force keeping write barrier for strict fsync mode | From | Chao Yu <> | Date | Tue, 20 Jul 2021 09:19:10 +0800 |
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On 2021/7/20 9:15, Jaegeuk Kim wrote: > Wasn't it supposed to be v1?
I skip IPU case for v1, and resend it as v3, is it fine to you?
Thanks,
> > On 07/20, Chao Yu wrote: >> [1] https://www.mail-archive.com/linux-f2fs-devel@lists.sourceforge.net/msg15126.html >> >> As [1] reported, if lower device doesn't support write barrier, in below >> case: >> >> - write page #0; persist >> - overwrite page #0 >> - fsync >> - write data page #0 OPU into device's cache >> - write inode page into device's cache >> - issue flush >> >> If SPO is triggered during flush command, inode page can be persisted >> before data page #0, so that after recovery, inode page can be recovered >> with new physical block address of data page #0, however there may >> contains dummy data in new physical block address. >> >> Then what user will see is: after overwrite & fsync + SPO, old data in >> file was corrupted, if any user do care about such case, we can suggest >> user to use STRICT fsync mode, in this mode, we will force to use atomic >> write sematics to keep write order in between data/node and last node, >> so that it avoids potential data corruption during fsync(). >> >> Signed-off-by: Chao Yu <chao@kernel.org> >> --- >> fs/f2fs/file.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >> index 6afd4562335f..00b45876eaa1 100644 >> --- a/fs/f2fs/file.c >> +++ b/fs/f2fs/file.c >> @@ -301,6 +301,18 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end, >> f2fs_exist_written_data(sbi, ino, UPDATE_INO)) >> goto flush_out; >> goto out; >> + } else { >> + /* >> + * for OPU case, during fsync(), node can be persisted before >> + * data when lower device doesn't support write barrier, result >> + * in data corruption after SPO. >> + * So for strict fsync mode, force to use atomic write sematics >> + * to keep write order in between data/node and last node to >> + * avoid potential data corruption. >> + */ >> + if (F2FS_OPTION(sbi).fsync_mode == >> + FSYNC_MODE_STRICT && !atomic) >> + atomic = true; >> } >> go_write: >> /* >> -- >> 2.22.1
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