| Message ID | 1397443448-20367-1-git-send-email-quwenruo@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On 04/13/2014 10:44 PM, Qu Wenruo wrote: > When testing fsstress with snapshot making background, some snapshot > following problem. > > Snapshot 270: > inode 323: size 0 > > Snapshot 271: > inode 323: size 349145 > |-------Hole---|---------Empty gap-------|-------Hole-----| > 0 122880 172032 349145 > > Snapshot 272: > inode 323: size 349145 > |-------Hole---|------------Data---------|-------Hole-----| > 0 122880 172032 349145 > > The fsstress operation on inode 323 is the following: > write: offset 126832 len 43124 > truncate: size 349145 > > Since the write with offset is consist of 2 operations: > 1. punch hole > 2. write data > Hole punching is faster than data write, so hole punching in write > and truncate is done first and then buffered write, so the snapshot 271 got > empty gap, which will not pass btrfsck. > > To fix the bug, this patch will change the write sequence which will > first punch a hole covering the write end if a hole is needed. > > Reported-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com> > Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> > Cc: Al Viro <viro@ZenIV.linux.org.uk> > Signed-off-by: Chris Mason <clm@fb.com> > --- > changelog: > v2: > Use 'pos + count' instead of 'pos + iov->iov_len' to deal with > multi-seg iov. Thanks for the review Al. Qu, could you please send an incremental? -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 036f506c..e7e78fa 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1727,6 +1727,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, struct btrfs_root *root = BTRFS_I(inode)->root; loff_t *ppos = &iocb->ki_pos; u64 start_pos; + u64 end_pos; ssize_t num_written = 0; ssize_t err = 0; size_t count, ocount; @@ -1781,7 +1782,9 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, start_pos = round_down(pos, root->sectorsize); if (start_pos > i_size_read(inode)) { - err = btrfs_cont_expand(inode, i_size_read(inode), start_pos); + /* Expand hole size to cover write data, preventing empty gap */ + end_pos = round_up(pos + count, root->sectorsize); + err = btrfs_cont_expand(inode, i_size_read(inode), end_pos); if (err) { mutex_unlock(&inode->i_mutex); goto out;