Btrfs: fix the file extent gap when doing direct IO
When we write some data to the place that is beyond the end of the file
in direct I/O mode, a data hole will be created. And Btrfs should insert
a file extent item that point to this hole into the fs tree. But unfortunately
Btrfs forgets doing it.
The following is a simple way to reproduce it:
# mkfs.btrfs /dev/sdc2
# mount /dev/sdc2 /test4
# touch /test4/a
# dd if=/dev/zero of=/test4/a seek=8 count=1 bs=4K oflag=direct conv=nocreat,notrunc
# umount /test4
# btrfsck /dev/sdc2
root 5 inode 257 errors 100
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Tested-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 15e5a1c..98d95bb 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1075,12 +1075,6 @@
start_pos = pos & ~((u64)root->sectorsize - 1);
last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
- if (start_pos > inode->i_size) {
- err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
- if (err)
- return err;
- }
-
again:
for (i = 0; i < num_pages; i++) {
pages[i] = find_or_create_page(inode->i_mapping, index + i,
@@ -1338,6 +1332,7 @@
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
loff_t *ppos = &iocb->ki_pos;
+ u64 start_pos;
ssize_t num_written = 0;
ssize_t err = 0;
size_t count, ocount;
@@ -1386,6 +1381,15 @@
file_update_time(file);
BTRFS_I(inode)->sequence++;
+ 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);
+ if (err) {
+ mutex_unlock(&inode->i_mutex);
+ goto out;
+ }
+ }
+
if (unlikely(file->f_flags & O_DIRECT)) {
num_written = __btrfs_direct_write(iocb, iov, nr_segs,
pos, ppos, count, ocount);