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fs: always maintain i_dio_count

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Maintain i_dio_count for all filesystems, not just those using DIO_LOCKING.
This these filesystems to also protect truncate against direct I/O requests
by using common code.  Right now the only non-DIO_LOCKING filesystem that
appears to do so is XFS, which uses an opencoded variant of the i_dio_count
scheme.

Behaviour doesn't change for filesystems never calling inode_dio_wait.
For ext4 behaviour changes when using the dioread_nonlock option, which
previously was missing any protection between truncate and direct I/O reads.
For ocfs2 that handcrafted i_dio_count manipulations are replaced with
the common code now enable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig
2011-06-24 14:29:46 -04:00
committed by Al Viro
parent 562c72aa57
commit df2d6f2658
3 changed files with 17 additions and 24 deletions
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12
fs/ocfs2/file.c
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@@ -2240,7 +2240,6 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
relock:
/* to match setattr's i_mutex -> rw_lock ordering */
if (direct_io) {
atomic_inc(&inode->i_dio_count);
have_alloc_sem = 1;
/* communicate with ocfs2_dio_end_io */
ocfs2_iocb_set_sem_locked(iocb);
@@ -2292,7 +2291,6 @@ relock:
*/
if (direct_io && !can_do_direct) {
ocfs2_rw_unlock(inode, rw_level);
inode_dio_done(inode);
have_alloc_sem = 0;
rw_level = -1;
@@ -2379,10 +2377,8 @@ out:
ocfs2_rw_unlock(inode, rw_level);
out_sems:
if (have_alloc_sem) {
inode_dio_done(inode);
if (have_alloc_sem)
ocfs2_iocb_clear_sem_locked(iocb);
}
mutex_unlock(&inode->i_mutex);
@@ -2533,7 +2529,6 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb,
*/
if (filp->f_flags & O_DIRECT) {
have_alloc_sem = 1;
atomic_inc(&inode->i_dio_count);
ocfs2_iocb_set_sem_locked(iocb);
ret = ocfs2_rw_lock(inode, 0);
@@ -2575,10 +2570,9 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb,
}
bail:
if (have_alloc_sem) {
inode_dio_done(inode);
if (have_alloc_sem)
ocfs2_iocb_clear_sem_locked(iocb);
}
if (rw_level != -1)
ocfs2_rw_unlock(inode, rw_level);