@@ -1718,6 +1718,7 @@ 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;
@@ -1772,7 +1773,9 @@ 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 + iov->iov_len, root->sectorsize);
+ err = btrfs_cont_expand(inode, i_size_read(inode), end_pos);
if (err) {
mutex_unlock(&inode->i_mutex);
goto out;
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> --- fs/btrfs/file.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)