fs: support RWF_NOWAIT for buffered reads
This is based on the old idea and code from Milosz Tanski. With the aio
nowait code it becomes mostly trivial now. Buffered writes continue to
return -EOPNOTSUPP if RWF_NOWAIT is passed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/aio.c b/fs/aio.c
index dcad3a6..d93daa0 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1593,12 +1593,6 @@
goto out_put_req;
}
- if ((req->common.ki_flags & IOCB_NOWAIT) &&
- !(req->common.ki_flags & IOCB_DIRECT)) {
- ret = -EOPNOTSUPP;
- goto out_put_req;
- }
-
ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
if (unlikely(ret)) {
pr_debug("EFAULT: aio_key\n");
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 9e75d8a..e62dd55 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1886,6 +1886,10 @@
loff_t oldsize;
int clean_page = 0;
+ if (!(iocb->ki_flags & IOCB_DIRECT) &&
+ (iocb->ki_flags & IOCB_NOWAIT))
+ return -EOPNOTSUPP;
+
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
return -EAGAIN;
@@ -3105,7 +3109,7 @@
static int btrfs_file_open(struct inode *inode, struct file *filp)
{
- filp->f_mode |= FMODE_AIO_NOWAIT;
+ filp->f_mode |= FMODE_NOWAIT;
return generic_file_open(inode, filp);
}
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 0d7cf0c..f835213 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -223,6 +223,8 @@
if (IS_DAX(inode))
return ext4_dax_write_iter(iocb, from);
#endif
+ if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
+ return -EOPNOTSUPP;
if (!inode_trylock(inode)) {
if (iocb->ki_flags & IOCB_NOWAIT)
@@ -448,9 +450,7 @@
return ret;
}
- /* Set the flags to support nowait AIO */
- filp->f_mode |= FMODE_AIO_NOWAIT;
-
+ filp->f_mode |= FMODE_NOWAIT;
return dquot_file_open(inode, filp);
}
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c4893e2..1a09104 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -259,7 +259,11 @@
trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
- xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ }
ret = generic_file_read_iter(iocb, to);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
@@ -636,6 +640,9 @@
int enospc = 0;
int iolock;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
write_retry:
iolock = XFS_IOLOCK_EXCL;
xfs_ilock(ip, iolock);
@@ -912,7 +919,7 @@
return -EFBIG;
if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
return -EIO;
- file->f_mode |= FMODE_AIO_NOWAIT;
+ file->f_mode |= FMODE_NOWAIT;
return 0;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index cbfe127..94582c3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -146,8 +146,8 @@
/* File was opened by fanotify and shouldn't generate fanotify events */
#define FMODE_NONOTIFY ((__force fmode_t)0x4000000)
-/* File is capable of returning -EAGAIN if AIO will block */
-#define FMODE_AIO_NOWAIT ((__force fmode_t)0x8000000)
+/* File is capable of returning -EAGAIN if I/O will block */
+#define FMODE_NOWAIT ((__force fmode_t)0x8000000)
/*
* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
@@ -3149,7 +3149,7 @@
return -EOPNOTSUPP;
if (flags & RWF_NOWAIT) {
- if (!(ki->ki_filp->f_mode & FMODE_AIO_NOWAIT))
+ if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
return -EOPNOTSUPP;
ki->ki_flags |= IOCB_NOWAIT;
}