Btrfs: fix the file extent gap when doing direct IO
PATCH 2/3 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 <[email protected]>
Signed-off-by Miao Xie <[email protected]>
Tested-by Tsutomu Itoh <[email protected]>
--- fs/btrfs/file.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-)
fs/btrfs/file.c +10 -6
@@ -1073,12 +1073,6 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file, 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,
@@ -1336,6 +1330,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,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;
@@ -1384,6 +1379,15 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,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);
Signature · 1 line
1.7.4
Quoted 26 lines
fs/btrfs/file.c +1
-6@@ -1073,12 +1073,6 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file, 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,@@ -1336,6 +1330,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,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;
fs/btrfs/file.c static ssize_t btrfs_file_aio_write(struct kiocb *iocb, · line 1383
Quoted 5 lines
fs/btrfs/file.c +2
-0@@ -1384,6 +1379,15 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,file_update_time (file);BTRFS_I (inode)->sequence++; + start_pos =round_down (pos, root->sectorsize); +if (start_pos >i_size_read (inode)) {
You changed the code to use i_size_read() instead of inode->i_size, which is not necessary since we're holding i_mutex.
fs/btrfs/file.c static ssize_t btrfs_file_aio_write(struct kiocb *iocb, · line 1384
Quoted 1 line
fs/btrfs/file.c +1
-0+ err =btrfs_cont_expand (inode,i_size_read (inode), start_pos);
So here we can also use inode->i_size directly.
Quoted 9 lines
fs/btrfs/file.c +6
-0+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);