Re: [PATCH 04/10] fs: Introduce RWF_NOWAIT
On Tue, Jun 06, 2017 at 06:19:33AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues
>
> RWF_NOWAIT informs kernel to bail out if an AIO request will block
> for reasons such as file allocations, or a writeback triggered,
> or would block while allocating requests while performing
> direct I/O.
>
> RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
>
> The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
> is called by most filesystems, either through fsops.write_iter() or through
> the function defined by write_iter(). If not, we perform the check defined
> by .write_iter() which is called for direct IO specifically.
>
> Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Umm... What about ->write_iter() instances outside of fs/*? Even in fs/*,
consider e.g.
int cifs_get_writer(struct cifsInodeInfo *cinode)
{
int rc;
start:
rc = wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_OPLOCK_BREAK,
TASK_KILLABLE);
and cifs_file_write_iter() calling it before going to generic_file_write_iter().
Ditto for cifs_struct_writev()... coda_file_write_iter() does inode_lock()
before calling vfs_iter_write(). ext2_dax_write_iter(): inode_lock().
f2fs_file_write_iter(): ditto. fuse_file_write_iter(): ditto in case when
->writeback_cache is false. gfs2 is O_APPEND case: almost certainly blocks.
ncp_file_write_iter(): blocks (mutex_lock(&NCP_FINFO(inode)->open_mutex)
in ncp_make_open(), not to mention anything else). ntfs_file_write_iter():
inode_lock(). orangefs_file_write_iter(): ditto. ubifs_write_iter():
may block in update_mctime(). udf_file_write_iter(): inode_lock().
Lustre sure as hell does block before it gets anywhere near mm/filemap.c.
And that - just from looking at regular files. Then we have sockets and
pipes, not to mention weird stuff like fs/fuse/cuse.c, etc.
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[PATCH 04/10] fs: Introduce RWF_NOWAIT
From: Goldwyn Rodrigues
RWF_NOWAIT informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
is called by most filesystems, either through fsops.write_iter() or through
the function defined by write_iter(). If not, we perform the check defined
by .write_iter() which is called for direct IO specifically.
Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Reviewed-by: Christoph Hellwig
Reviewed-by: Jan Kara
Signed-off-by: Goldwyn Rodrigues
---
fs/9p/vfs_file.c| 3 +++
fs/aio.c| 6 ++
fs/ceph/file.c | 3 +++
fs/cifs/file.c | 3 +++
fs/fuse/file.c | 3 +++
fs/nfs/direct.c | 3 +++
fs/ocfs2/file.c | 3 +++
include/linux/fs.h | 5 -
include/uapi/linux/fs.h | 1 +
mm/filemap.c| 3 +++
10 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3de3b4a89d89..403681db7723 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter
*from)
loff_t origin;
int err = 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
retval = generic_write_checks(iocb, from);
if (retval <= 0)
return retval;
diff --git a/fs/aio.c b/fs/aio.c
index 020fa0045e3c..34027b67e2f4 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
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/ceph/file.c b/fs/ceph/file.c
index 29308a80d66f..366b0bb71f97 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1300,6 +1300,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct
iov_iter *from)
int err, want, got;
loff_t pos;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EROFS;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0fd081bd2a2f..ff84fa9ddb6c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2725,6 +2725,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct
iov_iter *from)
* write request.
*/
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
rc = generic_write_checks(iocb, from);
if (rc <= 0)
return rc;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3ee4fdc3da9e..812c7bd0c290 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb,
struct iov_iter *from)
struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
ssize_t res;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (is_bad_inode(inode))
return -EIO;
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 6fb9fad2d1e6..c8e7dd76126c 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -979,6 +979,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct
iov_iter *iter)
dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
file, iov_iter_count(iter), (long long) iocb->ki_pos);
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
result = generic_write_checks(iocb, iter);
if (result <= 0)
return result;
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index bfeb647459d9..e7f8ba890305 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
if (count == 0)
return 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
inode_lock(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc0ab585cd56..2a7d14af6d12 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -268,6 +268,7 @@ struct writeback_control;
#define IOCB_DSYNC (1 << 4)
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
+#define IOCB_NOWAIT(1 << 7)
struct kiocb {
struct file *ki_filp;
@@ -3060,7 +3061,7 @@ static inline int iocb_flags(struct file *file)
static inline int kiocb_set_rw_flags(struct kiocb *ki, i
[PATCH 04/10] fs: Introduce RWF_NOWAIT
From: Goldwyn Rodrigues
RWF_NOWAIT informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
is called by most filesystems, either through fsops.write_iter() or through
the function defined by write_iter(). If not, we perform the check defined
by .write_iter() which is called for direct IO specifically.
Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Reviewed-by: Christoph Hellwig
Reviewed-by: Jan Kara
Signed-off-by: Goldwyn Rodrigues
---
fs/9p/vfs_file.c| 3 +++
fs/aio.c| 6 ++
fs/ceph/file.c | 3 +++
fs/cifs/file.c | 3 +++
fs/fuse/file.c | 3 +++
fs/nfs/direct.c | 3 +++
fs/ocfs2/file.c | 3 +++
include/linux/fs.h | 5 -
include/uapi/linux/fs.h | 1 +
mm/filemap.c| 3 +++
10 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3de3b4a89d89..403681db7723 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter
*from)
loff_t origin;
int err = 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
retval = generic_write_checks(iocb, from);
if (retval <= 0)
return retval;
diff --git a/fs/aio.c b/fs/aio.c
index 020fa0045e3c..34027b67e2f4 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
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/ceph/file.c b/fs/ceph/file.c
index 29308a80d66f..366b0bb71f97 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1300,6 +1300,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct
iov_iter *from)
int err, want, got;
loff_t pos;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EROFS;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0fd081bd2a2f..ff84fa9ddb6c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2725,6 +2725,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct
iov_iter *from)
* write request.
*/
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
rc = generic_write_checks(iocb, from);
if (rc <= 0)
return rc;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3ee4fdc3da9e..812c7bd0c290 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb,
struct iov_iter *from)
struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
ssize_t res;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (is_bad_inode(inode))
return -EIO;
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 6fb9fad2d1e6..c8e7dd76126c 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -979,6 +979,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct
iov_iter *iter)
dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
file, iov_iter_count(iter), (long long) iocb->ki_pos);
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
result = generic_write_checks(iocb, iter);
if (result <= 0)
return result;
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index bfeb647459d9..e7f8ba890305 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
if (count == 0)
return 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
inode_lock(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc0ab585cd56..2a7d14af6d12 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -268,6 +268,7 @@ struct writeback_control;
#define IOCB_DSYNC (1 << 4)
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
+#define IOCB_NOWAIT(1 << 7)
struct kiocb {
struct file *ki_filp;
@@ -3060,7 +3061,7 @@ static inline int iocb_flags(struct file *file)
static inline int kiocb_set_rw_flags(struct kiocb *ki, i
Re: [PATCH 04/10] fs: Introduce RWF_NOWAIT
On Wed 24-05-17 11:41:44, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues
>
> RWF_NOWAIT informs kernel to bail out if an AIO request will block
> for reasons such as file allocations, or a writeback triggered,
> or would block while allocating requests while performing
> direct I/O.
>
> RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
>
> The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
> is called by most filesystems, either through fsops.write_iter() or through
> the function defined by write_iter(). If not, we perform the check defined
> by .write_iter() which is called for direct IO specifically.
>
> Filesystems xfs, btrfs and ext4 would be supported in the following patches.
>
> Signed-off-by: Goldwyn Rodrigues
> Reviewed-by: Christoph Hellwig
Looks good now. You can add:
Reviewed-by: Jan Kara
Honza
> ---
> fs/9p/vfs_file.c| 3 +++
> fs/aio.c| 13 +
> fs/ceph/file.c | 3 +++
> fs/cifs/file.c | 3 +++
> fs/fuse/file.c | 3 +++
> fs/nfs/direct.c | 3 +++
> fs/ocfs2/file.c | 3 +++
> include/linux/fs.h | 5 -
> include/uapi/linux/fs.h | 1 +
> mm/filemap.c| 3 +++
> 10 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
> index 3de3b4a89d89..403681db7723 100644
> --- a/fs/9p/vfs_file.c
> +++ b/fs/9p/vfs_file.c
> @@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter
> *from)
> loff_t origin;
> int err = 0;
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> retval = generic_write_checks(iocb, from);
> if (retval <= 0)
> return retval;
> diff --git a/fs/aio.c b/fs/aio.c
> index 020fa0045e3c..9616dc733103 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1592,6 +1592,19 @@ static int io_submit_one(struct kioctx *ctx, struct
> iocb __user *user_iocb,
> goto out_put_req;
> }
>
> + if (req->common.ki_flags & IOCB_NOWAIT) {
> + if (!(req->common.ki_flags & IOCB_DIRECT)) {
> + ret = -EOPNOTSUPP;
> + goto out_put_req;
> + }
> +
> + if ((iocb->aio_lio_opcode != IOCB_CMD_PWRITE) &&
> + (iocb->aio_lio_opcode != IOCB_CMD_PWRITEV)) {
> + ret = -EINVAL;
> + 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/ceph/file.c b/fs/ceph/file.c
> index 3fdde0b283c9..a53fd2675b1b 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -1300,6 +1300,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb,
> struct iov_iter *from)
> int err, want, got;
> loff_t pos;
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> if (ceph_snap(inode) != CEPH_NOSNAP)
> return -EROFS;
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 0fd081bd2a2f..ff84fa9ddb6c 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2725,6 +2725,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct
> iov_iter *from)
>* write request.
>*/
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> rc = generic_write_checks(iocb, from);
> if (rc <= 0)
> return rc;
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 3ee4fdc3da9e..812c7bd0c290 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb
> *iocb, struct iov_iter *from)
> struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
> ssize_t res;
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> if (is_bad_inode(inode))
> return -EIO;
>
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index 6fb9fad2d1e6..c8e7dd76126c 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -979,6 +979,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct
> iov_iter *iter)
> dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
> file, iov_iter_count(iter), (long long) iocb->ki_pos);
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> result = generic_write_checks(iocb, iter);
> if (result <= 0)
> return result;
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index bfeb647459d9..e7f8ba890305 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
> if (count == 0)
> return 0;
>
> + if (iocb->ki_flags & IOCB_NOWAIT)
> + return -EOPNOTSUPP;
> +
> direct_io =
[PATCH 04/10] fs: Introduce RWF_NOWAIT
From: Goldwyn Rodrigues
RWF_NOWAIT informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
is called by most filesystems, either through fsops.write_iter() or through
the function defined by write_iter(). If not, we perform the check defined
by .write_iter() which is called for direct IO specifically.
Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Signed-off-by: Goldwyn Rodrigues
Reviewed-by: Christoph Hellwig
---
fs/9p/vfs_file.c| 3 +++
fs/aio.c| 13 +
fs/ceph/file.c | 3 +++
fs/cifs/file.c | 3 +++
fs/fuse/file.c | 3 +++
fs/nfs/direct.c | 3 +++
fs/ocfs2/file.c | 3 +++
include/linux/fs.h | 5 -
include/uapi/linux/fs.h | 1 +
mm/filemap.c| 3 +++
10 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3de3b4a89d89..403681db7723 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter
*from)
loff_t origin;
int err = 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
retval = generic_write_checks(iocb, from);
if (retval <= 0)
return retval;
diff --git a/fs/aio.c b/fs/aio.c
index 020fa0045e3c..9616dc733103 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1592,6 +1592,19 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
goto out_put_req;
}
+ if (req->common.ki_flags & IOCB_NOWAIT) {
+ if (!(req->common.ki_flags & IOCB_DIRECT)) {
+ ret = -EOPNOTSUPP;
+ goto out_put_req;
+ }
+
+ if ((iocb->aio_lio_opcode != IOCB_CMD_PWRITE) &&
+ (iocb->aio_lio_opcode != IOCB_CMD_PWRITEV)) {
+ ret = -EINVAL;
+ 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/ceph/file.c b/fs/ceph/file.c
index 3fdde0b283c9..a53fd2675b1b 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1300,6 +1300,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct
iov_iter *from)
int err, want, got;
loff_t pos;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EROFS;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0fd081bd2a2f..ff84fa9ddb6c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2725,6 +2725,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct
iov_iter *from)
* write request.
*/
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
rc = generic_write_checks(iocb, from);
if (rc <= 0)
return rc;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 3ee4fdc3da9e..812c7bd0c290 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb,
struct iov_iter *from)
struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
ssize_t res;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (is_bad_inode(inode))
return -EIO;
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 6fb9fad2d1e6..c8e7dd76126c 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -979,6 +979,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct
iov_iter *iter)
dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
file, iov_iter_count(iter), (long long) iocb->ki_pos);
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
result = generic_write_checks(iocb, iter);
if (result <= 0)
return result;
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index bfeb647459d9..e7f8ba890305 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
if (count == 0)
return 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
inode_lock(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dc0ab585cd56..2a7d14af6d12 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -268,6 +268,7 @@ struct writeback_control;
#define IOCB_DSYNC (1 << 4)
#define IOCB_SYNC (1 << 5)
#define IOCB_WRI
Re: [PATCH 04/10] fs: Introduce RWF_NOWAIT
On Thu 11-05-17 14:17:04, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues
>
> RWF_NOWAIT informs kernel to bail out if an AIO request will block
> for reasons such as file allocations, or a writeback triggered,
> or would block while allocating requests while performing
> direct I/O.
>
> RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
>
> The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
> is called by most filesystems, either through fsops.write_iter() or through
> the function defined by write_iter(). If not, we perform the check defined
> by .write_iter() which is called for direct IO specifically.
>
> Filesystems xfs, btrfs and ext4 would be supported in the following patches.
...
> diff --git a/fs/aio.c b/fs/aio.c
> index 020fa0045e3c..34027b67e2f4 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct
> iocb __user *user_iocb,
> 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");
I think you need to also check here that the IO is write. So that NOWAIT
reads don't silently pass.
Honza
--
Jan Kara
SUSE Labs, CR
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[PATCH 04/10] fs: Introduce RWF_NOWAIT
From: Goldwyn Rodrigues
RWF_NOWAIT informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags.
The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This
is called by most filesystems, either through fsops.write_iter() or through
the function defined by write_iter(). If not, we perform the check defined
by .write_iter() which is called for direct IO specifically.
Filesystems xfs, btrfs and ext4 would be supported in the following patches.
Signed-off-by: Goldwyn Rodrigues
Reviewed-by: Christoph Hellwig
---
fs/9p/vfs_file.c| 3 +++
fs/aio.c| 6 ++
fs/ceph/file.c | 3 +++
fs/cifs/file.c | 3 +++
fs/fuse/file.c | 3 +++
fs/nfs/direct.c | 3 +++
fs/ocfs2/file.c | 3 +++
include/linux/fs.h | 5 -
include/uapi/linux/fs.h | 1 +
mm/filemap.c| 3 +++
10 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3de3b4a89d89..403681db7723 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter
*from)
loff_t origin;
int err = 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
retval = generic_write_checks(iocb, from);
if (retval <= 0)
return retval;
diff --git a/fs/aio.c b/fs/aio.c
index 020fa0045e3c..34027b67e2f4 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb
__user *user_iocb,
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/ceph/file.c b/fs/ceph/file.c
index 26cc95421cca..af28419b1731 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1267,6 +1267,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct
iov_iter *from)
int err, want, got;
loff_t pos;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EROFS;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 21d404535739..f8858a06e119 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2638,6 +2638,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct
iov_iter *from)
* write request.
*/
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
rc = generic_write_checks(iocb, from);
if (rc <= 0)
return rc;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ec238fb5a584..72786e798319 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb,
struct iov_iter *from)
struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
ssize_t res;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
if (is_bad_inode(inode))
return -EIO;
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index c1b5fed7c863..dcea0caa5cb5 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -996,6 +996,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct
iov_iter *iter)
dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
file, iov_iter_count(iter), (long long) iocb->ki_pos);
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
result = generic_write_checks(iocb, iter);
if (result <= 0)
return result;
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index bfeb647459d9..e7f8ba890305 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
if (count == 0)
return 0;
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EOPNOTSUPP;
+
direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0;
inode_lock(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2e6fc6a23f91..7e39b510b7a4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -270,6 +270,7 @@ struct writeback_control;
#define IOCB_DSYNC (1 << 4)
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
+#define IOCB_NOWAIT(1 << 7)
struct kiocb {
struct file *ki_filp;
@@ -3053,7 +3054,7 @@ static inline int iocb_flags(struct file *file)
static inline int kiocb_set_rw_flags(struct kiocb *ki, int flags)
{
- if
