[PATCH v5 4/7] vfs: RWF_NONBLOCK flag for preadv2

[PATCH v5 4/7] vfs: RWF_NONBLOCK flag for preadv2

[Milosz Tanski]

generic_file_read_iter() supports a new flag RWF_NONBLOCK which says that we
only want to read the data if it's already in the page cache.

Additionally, there are a few filesystems that we have to specifically
bail early if RWF_NONBLOCK because the op would block. Christoph Hellwig
contributed this code.

Signed-off-by: Milosz Tanski <milosz@adfin.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
---
 fs/ceph/file.c     |  2 ++
 fs/cifs/file.c     |  6 ++++++
 fs/nfs/file.c      |  5 ++++-
 fs/ocfs2/file.c    |  6 ++++++
 fs/pipe.c          |  3 ++-
 fs/read_write.c    | 38 +++++++++++++++++++++++++-------------
 fs/xfs/xfs_file.c  |  4 ++++
 include/linux/fs.h |  3 +++
 mm/filemap.c       | 18 ++++++++++++++++++
 mm/shmem.c         |  4 ++++
 10 files changed, 74 insertions(+), 15 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index d7e0da8..b798b5c 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -822,6 +822,8 @@ again:
 	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
 	    (iocb->ki_filp->f_flags & O_DIRECT) ||
 	    (fi->flags & CEPH_F_SYNC)) {
+		if (iocb->ki_rwflags & O_NONBLOCK)
+			return -EAGAIN;
 
 		dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n",
 		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 3e4d00a..c485afa 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3005,6 +3005,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
 	struct cifs_readdata *rdata, *tmp;
 	struct list_head rdata_list;
 
+	if (iocb->ki_rwflags & RWF_NONBLOCK)
+		return -EAGAIN;
+
 	len = iov_iter_count(to);
 	if (!len)
 		return 0;
@@ -3123,6 +3126,9 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
 	    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
 		return generic_file_read_iter(iocb, to);
 
+	if (iocb->ki_rwflags & RWF_NONBLOCK)
+		return -EAGAIN;
+
 	/*
 	 * We need to hold the sem to be sure nobody modifies lock list
 	 * with a brlock that prevents reading.
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 2ab6f00..aa9046f 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -171,8 +171,11 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
 	struct inode *inode = file_inode(iocb->ki_filp);
 	ssize_t result;
 
-	if (iocb->ki_filp->f_flags & O_DIRECT)
+	if (iocb->ki_filp->f_flags & O_DIRECT) {
+		if (iocb->ki_rwflags & O_NONBLOCK)
+			return -EAGAIN;
 		return nfs_file_direct_read(iocb, to, iocb->ki_pos);
+	}
 
 	dprintk("NFS: read(%pD2, %zu@%lu)\n",
 		iocb->ki_filp,
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 324dc93..bb66ca4 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2472,6 +2472,12 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
 			filp->f_path.dentry->d_name.name,
 			to->nr_segs);	/* GRRRRR */
 
+	/*
+	 * No non-blocking reads for ocfs2 for now.  Might be doable with
+	 * non-blocking cluster lock helpers.
+	 */
+	if (iocb->ki_rwflags & RWF_NONBLOCK)
+		return -EAGAIN;
 
 	if (!inode) {
 		ret = -EINVAL;
diff --git a/fs/pipe.c b/fs/pipe.c
index 21981e5..212bf68 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -302,7 +302,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
 			 */
 			if (ret)
 				break;
-			if (filp->f_flags & O_NONBLOCK) {
+			if ((filp->f_flags & O_NONBLOCK) ||
+			    (iocb->ki_rwflags & RWF_NONBLOCK)) {
 				ret = -EAGAIN;
 				break;
 			}
diff --git a/fs/read_write.c b/fs/read_write.c
index 907735c..cba7d4c 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -835,14 +835,19 @@ static ssize_t do_readv_writev(int type, struct file *file,
 		file_start_write(file);
 	}
 
-	if (iter_fn)
+	if (iter_fn) {
 		ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
 						pos, iter_fn, flags);
-	else if (fnv)
-		ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
-						pos, fnv);
-	else
-		ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+	} else {
+		if (type == READ && (flags & RWF_NONBLOCK))
+			return -EAGAIN;
+
+		if (fnv)
+			ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
+							pos, fnv);
+		else
+			ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+	}
 
 	if (type != READ)
 		file_end_write(file);
@@ -866,8 +871,10 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))
 		return -EINVAL;
-	if (flags & ~0)
+	if (flags & ~RWF_NONBLOCK)
 		return -EINVAL;
+	if ((file->f_flags & O_DIRECT) && (flags & RWF_NONBLOCK))
+		return -EAGAIN;
 
 	return do_readv_writev(READ, file, vec, vlen, pos, flags);
 }
@@ -1069,14 +1076,19 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
 		file_start_write(file);
 	}
 
-	if (iter_fn)
+	if (iter_fn) {
 		ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
 						pos, iter_fn, flags);
-	else if (fnv)
-		ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
-						pos, fnv);
-	else
-		ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+	} else {
+		if (type == READ && (flags & RWF_NONBLOCK))
+			return -EAGAIN;
+
+		if (fnv)
+			ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
+							pos, fnv);
+		else
+			ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+	}
 
 	if (type != READ)
 		file_end_write(file);
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index eb596b4..b1f6334 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -246,6 +246,10 @@ xfs_file_read_iter(
 
 	XFS_STATS_INC(xs_read_calls);
 
+	/* XXX: need a non-blocking iolock helper, shouldn't be too hard */
+	if (iocb->ki_rwflags & RWF_NONBLOCK)
+		return -EAGAIN;
+
 	if (unlikely(file->f_flags & O_DIRECT))
 		ioflags |= XFS_IO_ISDIRECT;
 	if (file->f_mode & FMODE_NOCMTIME)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9ed5711..eaebd99 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1459,6 +1459,9 @@ struct block_device_operations;
 #define HAVE_COMPAT_IOCTL 1
 #define HAVE_UNLOCKED_IOCTL 1
 
+/* These flags are used for the readv/writev syscalls with flags. */
+#define RWF_NONBLOCK 0x00000001
+
 struct iov_iter;
 
 struct file_operations {
diff --git a/mm/filemap.c b/mm/filemap.c
index 530c263..09d3af3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1494,6 +1494,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
 find_page:
 		page = find_get_page(mapping, index);
 		if (!page) {
+			if (flags & RWF_NONBLOCK)
+				goto would_block;
 			page_cache_sync_readahead(mapping,
 					ra, filp,
 					index, last_index - index);
@@ -1585,6 +1587,11 @@ page_ok:
 		continue;
 
 page_not_up_to_date:
+		if (flags & RWF_NONBLOCK) {
+			page_cache_release(page);
+			goto would_block;
+		}
+
 		/* Get exclusive access to the page ... */
 		error = lock_page_killable(page);
 		if (unlikely(error))
@@ -1604,6 +1611,12 @@ page_not_up_to_date_locked:
 			goto page_ok;
 		}
 
+		if (flags & RWF_NONBLOCK) {
+			unlock_page(page);
+			page_cache_release(page);
+			goto would_block;
+		}
+
 readpage:
 		/*
 		 * A previous I/O error may have been due to temporary
@@ -1674,6 +1687,8 @@ no_cached_page:
 		goto readpage;
 	}
 
+would_block:
+	error = -EAGAIN;
 out:
 	ra->prev_pos = prev_index;
 	ra->prev_pos <<= PAGE_CACHE_SHIFT;
@@ -1707,6 +1722,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 		size_t count = iov_iter_count(iter);
 		loff_t size;
 
+		if (iocb->ki_rwflags & RWF_NONBLOCK)
+			return -EAGAIN;
+
 		if (!count)
 			goto out; /* skip atime */
 		size = i_size_read(inode);
diff --git a/mm/shmem.c b/mm/shmem.c
index cd6fc75..5c30f04 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1531,6 +1531,10 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	ssize_t retval = 0;
 	loff_t *ppos = &iocb->ki_pos;
 
+	/* XXX: should be easily supportable */
+	if (iocb->ki_rwflags & RWF_NONBLOCK)
+		return -EAGAIN;
+
 	/*
 	 * Might this read be for a stacking filesystem?  Then when reading
 	 * holes of a sparse file, we actually need to allocate those pages,
-- 
1.9.1

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[PATCH v5 6/7] fs: pass iocb to generic_write_sync

[Milosz Tanski]

From: Christoph Hellwig <hch@lst.de>

Clean up the generic_write_sync by just passing an iocb and a bytes
written / negative errno argument.  In addition to simplifying the
callers this also prepares for passing a per-operation O_DSYNC
flag.  Two callers didn't quite fit that scheme:

 - dio_complete didn't both to update ki_pos as we don't need it
   on a iocb that is about to be freed, so we had to add it. Additionally
   it also synced out written data in the error case, which has been
   changed to operate like the other callers.
 - gfs2 also used generic_write_sync to implement a crude version
   of fallocate.  It has been switched to use an open coded variant
   instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/block_dev.c     |  8 +-------
 fs/btrfs/file.c    |  7 ++-----
 fs/cifs/file.c     |  8 +-------
 fs/direct-io.c     |  8 ++------
 fs/ext4/file.c     |  8 +-------
 fs/gfs2/file.c     |  9 +++++++--
 fs/ntfs/file.c     |  8 ++------
 fs/udf/file.c      | 11 ++---------
 fs/xfs/xfs_file.c  |  8 +-------
 include/linux/fs.h |  8 +-------
 mm/filemap.c       | 30 ++++++++++++++++++++----------
 11 files changed, 40 insertions(+), 73 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index cc9d411..c529b1c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1568,18 +1568,12 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
  */
 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct file *file = iocb->ki_filp;
 	struct blk_plug plug;
 	ssize_t ret;
 
 	blk_start_plug(&plug);
 	ret = __generic_file_write_iter(iocb, from);
-	if (ret > 0) {
-		ssize_t err;
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
-	}
+	ret = generic_write_sync(iocb, ret);
 	blk_finish_plug(&plug);
 	return ret;
 }
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index a18ceab..4f4a6f7 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1820,11 +1820,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	 */
 	BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
 	BTRFS_I(inode)->last_sub_trans = root->log_transid;
-	if (num_written > 0) {
-		err = generic_write_sync(file, pos, num_written);
-		if (err < 0)
-			num_written = err;
-	}
+
+	num_written = generic_write_sync(iocb, num_written);
 
 	if (sync)
 		atomic_dec(&BTRFS_I(inode)->sync_writers);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index c485afa..32359de 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2706,13 +2706,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 		rc = __generic_file_write_iter(iocb, from);
 		mutex_unlock(&inode->i_mutex);
 
-		if (rc > 0) {
-			ssize_t err;
-
-			err = generic_write_sync(file, iocb->ki_pos - rc, rc);
-			if (err < 0)
-				rc = err;
-		}
+		rc = generic_write_sync(iocb, rc);
 	} else {
 		mutex_unlock(&inode->i_mutex);
 	}
diff --git a/fs/direct-io.c b/fs/direct-io.c
index e181b6b..b72ac83 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -257,12 +257,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
 	inode_dio_done(dio->inode);
 	if (is_async) {
 		if (dio->rw & WRITE) {
-			int err;
-
-			err = generic_write_sync(dio->iocb->ki_filp, offset,
-						 transferred);
-			if (err < 0 && ret > 0)
-				ret = err;
+			dio->iocb->ki_pos = offset + transferred;
+			ret = generic_write_sync(dio->iocb, ret);
 		}
 
 		aio_complete(dio->iocb, ret, 0);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index aca7b24..79b000c 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -175,13 +175,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ret = __generic_file_write_iter(iocb, from);
 	mutex_unlock(&inode->i_mutex);
 
-	if (ret > 0) {
-		ssize_t err;
-
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
-	}
+	ret = generic_write_sync(iocb, ret);
 	if (o_direct)
 		blk_finish_plug(&plug);
 
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 80dd44d..3fafeca 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -895,8 +895,13 @@ retry:
 		gfs2_quota_unlock(ip);
 	}
 
-	if (error == 0)
-		error = generic_write_sync(file, pos, count);
+	if (error)
+		goto out_unlock;
+
+	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host)) {
+		error = vfs_fsync_range(file, pos, pos + count - 1,
+			       (file->f_flags & __O_SYNC) ? 0 : 1);
+	}
 	goto out_unlock;
 
 out_trans_fail:
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 643faa4..4f3d664 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -2127,12 +2127,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	mutex_lock(&inode->i_mutex);
 	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
-	if (ret > 0) {
-		int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
-	}
-	return ret;
+
+	return generic_write_sync(iocb, ret);
 }
 
 /**
diff --git a/fs/udf/file.c b/fs/udf/file.c
index bb15771..1cdabd0 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -155,16 +155,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	retval = __generic_file_write_iter(iocb, from);
 	mutex_unlock(&inode->i_mutex);
 
-	if (retval > 0) {
-		ssize_t err;
-
+	if (retval > 0)
 		mark_inode_dirty(inode);
-		err = generic_write_sync(file, iocb->ki_pos - retval, retval);
-		if (err < 0)
-			retval = err;
-	}
-
-	return retval;
+	return generic_write_sync(iocb, retval);
 }
 
 long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 0655915..a8cab66 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -792,14 +792,8 @@ xfs_file_write_iter(
 		ret = xfs_file_buffered_aio_write(iocb, from);
 
 	if (ret > 0) {
-		ssize_t err;
-
 		XFS_STATS_ADD(xs_write_bytes, ret);
-
-		/* Handle various SYNC-type writes */
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
+		ret = generic_write_sync(iocb, ret);
 	}
 	return ret;
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index eaebd99..7d0e116 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2242,13 +2242,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
 			   int datasync);
 extern int vfs_fsync(struct file *file, int datasync);
-static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
-{
-	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
-		return 0;
-	return vfs_fsync_range(file, pos, pos + count - 1,
-			       (file->f_flags & __O_SYNC) ? 0 : 1);
-}
+extern int generic_write_sync(struct kiocb *iocb, loff_t count);
 extern void emergency_sync(void);
 extern void emergency_remount(void);
 #ifdef CONFIG_BLOCK
diff --git a/mm/filemap.c b/mm/filemap.c
index 09d3af3..6107058 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2664,6 +2664,24 @@ out:
 }
 EXPORT_SYMBOL(__generic_file_write_iter);
 
+int generic_write_sync(struct kiocb *iocb, loff_t count)
+{
+	struct file *file = iocb->ki_filp;
+
+	if (count > 0 &&
+	    ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))) {
+		bool fdatasync = !(file->f_flags & __O_SYNC);
+		ssize_t ret = 0;
+
+		ret = vfs_fsync_range(file, iocb->ki_pos - count,
+				iocb->ki_pos - 1, fdatasync);
+		if (ret < 0)
+			return ret;
+	}
+	return count;
+}
+EXPORT_SYMBOL(generic_write_sync);
+
 /**
  * generic_file_write_iter - write data to a file
  * @iocb:	IO state structure
@@ -2675,22 +2693,14 @@ EXPORT_SYMBOL(__generic_file_write_iter);
  */
 ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
+	struct inode *inode = iocb->ki_filp->f_mapping->host;
 	ssize_t ret;
 
 	mutex_lock(&inode->i_mutex);
 	ret = __generic_file_write_iter(iocb, from);
 	mutex_unlock(&inode->i_mutex);
 
-	if (ret > 0) {
-		ssize_t err;
-
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
-	}
-	return ret;
+	return generic_write_sync(iocb, ret);
 }
 EXPORT_SYMBOL(generic_file_write_iter);
 
-- 
1.9.1

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Re: [Cluster-devel] [PATCH v5 6/7] fs: pass iocb to generic_write_sync

[Steven Whitehouse]

Hi,

On 05/11/14 21:14, Milosz Tanski wrote:
> From: Christoph Hellwig <hch@lst.de>
>
> Clean up the generic_write_sync by just passing an iocb and a bytes
> written / negative errno argument.  In addition to simplifying the
> callers this also prepares for passing a per-operation O_DSYNC
> flag.  Two callers didn't quite fit that scheme:
>
>   - dio_complete didn't both to update ki_pos as we don't need it
>     on a iocb that is about to be freed, so we had to add it. Additionally
>     it also synced out written data in the error case, which has been
>     changed to operate like the other callers.
>   - gfs2 also used generic_write_sync to implement a crude version
>     of fallocate.  It has been switched to use an open coded variant
>     instead.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
GFS2 bits:

Acked-by: Steven Whitehouse <swhiteho@redhat.com>

I know that Andy Price has some work in this area too, so in due course 
we'll have to be careful not to create a merge conflict here. Copying in 
Andy so he can see the changes,

Steve.

> ---
>   fs/block_dev.c     |  8 +-------
>   fs/btrfs/file.c    |  7 ++-----
>   fs/cifs/file.c     |  8 +-------
>   fs/direct-io.c     |  8 ++------
>   fs/ext4/file.c     |  8 +-------
>   fs/gfs2/file.c     |  9 +++++++--
>   fs/ntfs/file.c     |  8 ++------
>   fs/udf/file.c      | 11 ++---------
>   fs/xfs/xfs_file.c  |  8 +-------
>   include/linux/fs.h |  8 +-------
>   mm/filemap.c       | 30 ++++++++++++++++++++----------
>   11 files changed, 40 insertions(+), 73 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index cc9d411..c529b1c 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1568,18 +1568,12 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>    */
>   ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   {
> -	struct file *file = iocb->ki_filp;
>   	struct blk_plug plug;
>   	ssize_t ret;
>   
>   	blk_start_plug(&plug);
>   	ret = __generic_file_write_iter(iocb, from);
> -	if (ret > 0) {
> -		ssize_t err;
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
>   	blk_finish_plug(&plug);
>   	return ret;
>   }
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index a18ceab..4f4a6f7 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1820,11 +1820,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
>   	 */
>   	BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
>   	BTRFS_I(inode)->last_sub_trans = root->log_transid;
> -	if (num_written > 0) {
> -		err = generic_write_sync(file, pos, num_written);
> -		if (err < 0)
> -			num_written = err;
> -	}
> +
> +	num_written = generic_write_sync(iocb, num_written);
>   
>   	if (sync)
>   		atomic_dec(&BTRFS_I(inode)->sync_writers);
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index c485afa..32359de 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2706,13 +2706,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
>   		rc = __generic_file_write_iter(iocb, from);
>   		mutex_unlock(&inode->i_mutex);
>   
> -		if (rc > 0) {
> -			ssize_t err;
> -
> -			err = generic_write_sync(file, iocb->ki_pos - rc, rc);
> -			if (err < 0)
> -				rc = err;
> -		}
> +		rc = generic_write_sync(iocb, rc);
>   	} else {
>   		mutex_unlock(&inode->i_mutex);
>   	}
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index e181b6b..b72ac83 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -257,12 +257,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
>   	inode_dio_done(dio->inode);
>   	if (is_async) {
>   		if (dio->rw & WRITE) {
> -			int err;
> -
> -			err = generic_write_sync(dio->iocb->ki_filp, offset,
> -						 transferred);
> -			if (err < 0 && ret > 0)
> -				ret = err;
> +			dio->iocb->ki_pos = offset + transferred;
> +			ret = generic_write_sync(dio->iocb, ret);
>   		}
>   
>   		aio_complete(dio->iocb, ret, 0);
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index aca7b24..79b000c 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -175,13 +175,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   	ret = __generic_file_write_iter(iocb, from);
>   	mutex_unlock(&inode->i_mutex);
>   
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
>   	if (o_direct)
>   		blk_finish_plug(&plug);
>   
> diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
> index 80dd44d..3fafeca 100644
> --- a/fs/gfs2/file.c
> +++ b/fs/gfs2/file.c
> @@ -895,8 +895,13 @@ retry:
>   		gfs2_quota_unlock(ip);
>   	}
>   
> -	if (error == 0)
> -		error = generic_write_sync(file, pos, count);
> +	if (error)
> +		goto out_unlock;
> +
> +	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host)) {
> +		error = vfs_fsync_range(file, pos, pos + count - 1,
> +			       (file->f_flags & __O_SYNC) ? 0 : 1);
> +	}
>   	goto out_unlock;
>   
>   out_trans_fail:
> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
> index 643faa4..4f3d664 100644
> --- a/fs/ntfs/file.c
> +++ b/fs/ntfs/file.c
> @@ -2127,12 +2127,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>   	mutex_lock(&inode->i_mutex);
>   	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
>   	mutex_unlock(&inode->i_mutex);
> -	if (ret > 0) {
> -		int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +
> +	return generic_write_sync(iocb, ret);
>   }
>   
>   /**
> diff --git a/fs/udf/file.c b/fs/udf/file.c
> index bb15771..1cdabd0 100644
> --- a/fs/udf/file.c
> +++ b/fs/udf/file.c
> @@ -155,16 +155,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   	retval = __generic_file_write_iter(iocb, from);
>   	mutex_unlock(&inode->i_mutex);
>   
> -	if (retval > 0) {
> -		ssize_t err;
> -
> +	if (retval > 0)
>   		mark_inode_dirty(inode);
> -		err = generic_write_sync(file, iocb->ki_pos - retval, retval);
> -		if (err < 0)
> -			retval = err;
> -	}
> -
> -	return retval;
> +	return generic_write_sync(iocb, retval);
>   }
>   
>   long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 0655915..a8cab66 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -792,14 +792,8 @@ xfs_file_write_iter(
>   		ret = xfs_file_buffered_aio_write(iocb, from);
>   
>   	if (ret > 0) {
> -		ssize_t err;
> -
>   		XFS_STATS_ADD(xs_write_bytes, ret);
> -
> -		/* Handle various SYNC-type writes */
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> +		ret = generic_write_sync(iocb, ret);
>   	}
>   	return ret;
>   }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index eaebd99..7d0e116 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2242,13 +2242,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
>   extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
>   			   int datasync);
>   extern int vfs_fsync(struct file *file, int datasync);
> -static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> -{
> -	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
> -		return 0;
> -	return vfs_fsync_range(file, pos, pos + count - 1,
> -			       (file->f_flags & __O_SYNC) ? 0 : 1);
> -}
> +extern int generic_write_sync(struct kiocb *iocb, loff_t count);
>   extern void emergency_sync(void);
>   extern void emergency_remount(void);
>   #ifdef CONFIG_BLOCK
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 09d3af3..6107058 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2664,6 +2664,24 @@ out:
>   }
>   EXPORT_SYMBOL(__generic_file_write_iter);
>   
> +int generic_write_sync(struct kiocb *iocb, loff_t count)
> +{
> +	struct file *file = iocb->ki_filp;
> +
> +	if (count > 0 &&
> +	    ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))) {
> +		bool fdatasync = !(file->f_flags & __O_SYNC);
> +		ssize_t ret = 0;
> +
> +		ret = vfs_fsync_range(file, iocb->ki_pos - count,
> +				iocb->ki_pos - 1, fdatasync);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	return count;
> +}
> +EXPORT_SYMBOL(generic_write_sync);
> +
>   /**
>    * generic_file_write_iter - write data to a file
>    * @iocb:	IO state structure
> @@ -2675,22 +2693,14 @@ EXPORT_SYMBOL(__generic_file_write_iter);
>    */
>   ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   {
> -	struct file *file = iocb->ki_filp;
> -	struct inode *inode = file->f_mapping->host;
> +	struct inode *inode = iocb->ki_filp->f_mapping->host;
>   	ssize_t ret;
>   
>   	mutex_lock(&inode->i_mutex);
>   	ret = __generic_file_write_iter(iocb, from);
>   	mutex_unlock(&inode->i_mutex);
>   
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +	return generic_write_sync(iocb, ret);
>   }
>   EXPORT_SYMBOL(generic_file_write_iter);
>   

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Re: [Linux-NTFS-Dev] [PATCH v5 6/7] fs: pass iocb to generic_write_sync

[Anton Altaparmakov]

Hi,

> On 5 Nov 2014, at 23:14, Milosz Tanski <milosz@adfin.com> wrote:
> 
> From: Christoph Hellwig <hch@lst.de>
> 
> Clean up the generic_write_sync by just passing an iocb and a bytes
> written / negative errno argument.  In addition to simplifying the
> callers this also prepares for passing a per-operation O_DSYNC
> flag.  Two callers didn't quite fit that scheme:
> 
> - dio_complete didn't both to update ki_pos as we don't need it
>   on a iocb that is about to be freed, so we had to add it. Additionally
>   it also synced out written data in the error case, which has been
>   changed to operate like the other callers.
> - gfs2 also used generic_write_sync to implement a crude version
>   of fallocate.  It has been switched to use an open coded variant
>   instead.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/block_dev.c     |  8 +-------
> fs/btrfs/file.c    |  7 ++-----
> fs/cifs/file.c     |  8 +-------
> fs/direct-io.c     |  8 ++------
> fs/ext4/file.c     |  8 +-------
> fs/gfs2/file.c     |  9 +++++++--
> fs/ntfs/file.c     |  8 ++------
> fs/udf/file.c      | 11 ++---------
> fs/xfs/xfs_file.c  |  8 +-------
> include/linux/fs.h |  8 +-------
> mm/filemap.c       | 30 ++++++++++++++++++++----------
> 11 files changed, 40 insertions(+), 73 deletions(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index cc9d411..c529b1c 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1568,18 +1568,12 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>  */
> ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> {
> -	struct file *file = iocb->ki_filp;
> 	struct blk_plug plug;
> 	ssize_t ret;
> 
> 	blk_start_plug(&plug);
> 	ret = __generic_file_write_iter(iocb, from);
> -	if (ret > 0) {
> -		ssize_t err;
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
> 	blk_finish_plug(&plug);
> 	return ret;
> }
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index a18ceab..4f4a6f7 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1820,11 +1820,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
> 	 */
> 	BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
> 	BTRFS_I(inode)->last_sub_trans = root->log_transid;
> -	if (num_written > 0) {
> -		err = generic_write_sync(file, pos, num_written);
> -		if (err < 0)
> -			num_written = err;
> -	}
> +
> +	num_written = generic_write_sync(iocb, num_written);
> 
> 	if (sync)
> 		atomic_dec(&BTRFS_I(inode)->sync_writers);
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index c485afa..32359de 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2706,13 +2706,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
> 		rc = __generic_file_write_iter(iocb, from);
> 		mutex_unlock(&inode->i_mutex);
> 
> -		if (rc > 0) {
> -			ssize_t err;
> -
> -			err = generic_write_sync(file, iocb->ki_pos - rc, rc);
> -			if (err < 0)
> -				rc = err;
> -		}
> +		rc = generic_write_sync(iocb, rc);
> 	} else {
> 		mutex_unlock(&inode->i_mutex);
> 	}
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index e181b6b..b72ac83 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -257,12 +257,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
> 	inode_dio_done(dio->inode);
> 	if (is_async) {
> 		if (dio->rw & WRITE) {
> -			int err;
> -
> -			err = generic_write_sync(dio->iocb->ki_filp, offset,
> -						 transferred);
> -			if (err < 0 && ret > 0)
> -				ret = err;
> +			dio->iocb->ki_pos = offset + transferred;
> +			ret = generic_write_sync(dio->iocb, ret);
> 		}
> 
> 		aio_complete(dio->iocb, ret, 0);
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index aca7b24..79b000c 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -175,13 +175,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> 	ret = __generic_file_write_iter(iocb, from);
> 	mutex_unlock(&inode->i_mutex);
> 
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
> 	if (o_direct)
> 		blk_finish_plug(&plug);
> 
> diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
> index 80dd44d..3fafeca 100644
> --- a/fs/gfs2/file.c
> +++ b/fs/gfs2/file.c
> @@ -895,8 +895,13 @@ retry:
> 		gfs2_quota_unlock(ip);
> 	}
> 
> -	if (error == 0)
> -		error = generic_write_sync(file, pos, count);
> +	if (error)
> +		goto out_unlock;
> +
> +	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host)) {
> +		error = vfs_fsync_range(file, pos, pos + count - 1,
> +			       (file->f_flags & __O_SYNC) ? 0 : 1);
> +	}
> 	goto out_unlock;
> 
> out_trans_fail:
> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
> index 643faa4..4f3d664 100644
> --- a/fs/ntfs/file.c
> +++ b/fs/ntfs/file.c
> @@ -2127,12 +2127,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
> 	mutex_lock(&inode->i_mutex);
> 	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
> 	mutex_unlock(&inode->i_mutex);
> -	if (ret > 0) {
> -		int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +
> +	return generic_write_sync(iocb, ret);
> }
> 
> /**
> diff --git a/fs/udf/file.c b/fs/udf/file.c
> index bb15771..1cdabd0 100644
> --- a/fs/udf/file.c
> +++ b/fs/udf/file.c
> @@ -155,16 +155,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> 	retval = __generic_file_write_iter(iocb, from);
> 	mutex_unlock(&inode->i_mutex);
> 
> -	if (retval > 0) {
> -		ssize_t err;
> -
> +	if (retval > 0)
> 		mark_inode_dirty(inode);
> -		err = generic_write_sync(file, iocb->ki_pos - retval, retval);
> -		if (err < 0)
> -			retval = err;
> -	}
> -
> -	return retval;
> +	return generic_write_sync(iocb, retval);
> }
> 
> long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 0655915..a8cab66 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -792,14 +792,8 @@ xfs_file_write_iter(
> 		ret = xfs_file_buffered_aio_write(iocb, from);
> 
> 	if (ret > 0) {
> -		ssize_t err;
> -
> 		XFS_STATS_ADD(xs_write_bytes, ret);
> -
> -		/* Handle various SYNC-type writes */
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> +		ret = generic_write_sync(iocb, ret);
> 	}
> 	return ret;
> }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index eaebd99..7d0e116 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2242,13 +2242,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
> extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
> 			   int datasync);
> extern int vfs_fsync(struct file *file, int datasync);
> -static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> -{
> -	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
> -		return 0;
> -	return vfs_fsync_range(file, pos, pos + count - 1,
> -			       (file->f_flags & __O_SYNC) ? 0 : 1);
> -}
> +extern int generic_write_sync(struct kiocb *iocb, loff_t count);
> extern void emergency_sync(void);
> extern void emergency_remount(void);
> #ifdef CONFIG_BLOCK
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 09d3af3..6107058 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2664,6 +2664,24 @@ out:
> }
> EXPORT_SYMBOL(__generic_file_write_iter);
> 
> +int generic_write_sync(struct kiocb *iocb, loff_t count)
> +{
> +	struct file *file = iocb->ki_filp;
> +
> +	if (count > 0 &&
> +	    ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))) {
> +		bool fdatasync = !(file->f_flags & __O_SYNC);
> +		ssize_t ret = 0;

That "= 0" is pointless.  "ret" is overwritten unconditionally on the following line...

Other than that the NTFS bits are:

Acked-by: Anton Altaparmakov <anton@tuxera.com>

Best regards,

	Anton

> +
> +		ret = vfs_fsync_range(file, iocb->ki_pos - count,
> +				iocb->ki_pos - 1, fdatasync);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	return count;
> +}
> +EXPORT_SYMBOL(generic_write_sync);
> +
> /**
>  * generic_file_write_iter - write data to a file
>  * @iocb:	IO state structure
> @@ -2675,22 +2693,14 @@ EXPORT_SYMBOL(__generic_file_write_iter);
>  */
> ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> {
> -	struct file *file = iocb->ki_filp;
> -	struct inode *inode = file->f_mapping->host;
> +	struct inode *inode = iocb->ki_filp->f_mapping->host;
> 	ssize_t ret;
> 
> 	mutex_lock(&inode->i_mutex);
> 	ret = __generic_file_write_iter(iocb, from);
> 	mutex_unlock(&inode->i_mutex);
> 
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +	return generic_write_sync(iocb, ret);
> }
> EXPORT_SYMBOL(generic_file_write_iter);

-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
University of Cambridge Information Services, Roger Needham Building
7 JJ Thomson Avenue, Cambridge, CB3 0RB, UK

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Re: [PATCH v5 6/7] fs: pass iocb to generic_write_sync

[Jan Kara]

On Wed 05-11-14 16:14:52, Milosz Tanski wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> Clean up the generic_write_sync by just passing an iocb and a bytes
> written / negative errno argument.  In addition to simplifying the
> callers this also prepares for passing a per-operation O_DSYNC
> flag.  Two callers didn't quite fit that scheme:
> 
>  - dio_complete didn't both to update ki_pos as we don't need it
>    on a iocb that is about to be freed, so we had to add it. Additionally
>    it also synced out written data in the error case, which has been
>    changed to operate like the other callers.
>  - gfs2 also used generic_write_sync to implement a crude version
>    of fallocate.  It has been switched to use an open coded variant
>    instead.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
  Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/block_dev.c     |  8 +-------
>  fs/btrfs/file.c    |  7 ++-----
>  fs/cifs/file.c     |  8 +-------
>  fs/direct-io.c     |  8 ++------
>  fs/ext4/file.c     |  8 +-------
>  fs/gfs2/file.c     |  9 +++++++--
>  fs/ntfs/file.c     |  8 ++------
>  fs/udf/file.c      | 11 ++---------
>  fs/xfs/xfs_file.c  |  8 +-------
>  include/linux/fs.h |  8 +-------
>  mm/filemap.c       | 30 ++++++++++++++++++++----------
>  11 files changed, 40 insertions(+), 73 deletions(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index cc9d411..c529b1c 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1568,18 +1568,12 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>   */
>  ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  {
> -	struct file *file = iocb->ki_filp;
>  	struct blk_plug plug;
>  	ssize_t ret;
>  
>  	blk_start_plug(&plug);
>  	ret = __generic_file_write_iter(iocb, from);
> -	if (ret > 0) {
> -		ssize_t err;
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
>  	blk_finish_plug(&plug);
>  	return ret;
>  }
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index a18ceab..4f4a6f7 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -1820,11 +1820,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
>  	 */
>  	BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
>  	BTRFS_I(inode)->last_sub_trans = root->log_transid;
> -	if (num_written > 0) {
> -		err = generic_write_sync(file, pos, num_written);
> -		if (err < 0)
> -			num_written = err;
> -	}
> +
> +	num_written = generic_write_sync(iocb, num_written);
>  
>  	if (sync)
>  		atomic_dec(&BTRFS_I(inode)->sync_writers);
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index c485afa..32359de 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2706,13 +2706,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
>  		rc = __generic_file_write_iter(iocb, from);
>  		mutex_unlock(&inode->i_mutex);
>  
> -		if (rc > 0) {
> -			ssize_t err;
> -
> -			err = generic_write_sync(file, iocb->ki_pos - rc, rc);
> -			if (err < 0)
> -				rc = err;
> -		}
> +		rc = generic_write_sync(iocb, rc);
>  	} else {
>  		mutex_unlock(&inode->i_mutex);
>  	}
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index e181b6b..b72ac83 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -257,12 +257,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
>  	inode_dio_done(dio->inode);
>  	if (is_async) {
>  		if (dio->rw & WRITE) {
> -			int err;
> -
> -			err = generic_write_sync(dio->iocb->ki_filp, offset,
> -						 transferred);
> -			if (err < 0 && ret > 0)
> -				ret = err;
> +			dio->iocb->ki_pos = offset + transferred;
> +			ret = generic_write_sync(dio->iocb, ret);
>  		}
>  
>  		aio_complete(dio->iocb, ret, 0);
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index aca7b24..79b000c 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -175,13 +175,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	ret = __generic_file_write_iter(iocb, from);
>  	mutex_unlock(&inode->i_mutex);
>  
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> +	ret = generic_write_sync(iocb, ret);
>  	if (o_direct)
>  		blk_finish_plug(&plug);
>  
> diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
> index 80dd44d..3fafeca 100644
> --- a/fs/gfs2/file.c
> +++ b/fs/gfs2/file.c
> @@ -895,8 +895,13 @@ retry:
>  		gfs2_quota_unlock(ip);
>  	}
>  
> -	if (error == 0)
> -		error = generic_write_sync(file, pos, count);
> +	if (error)
> +		goto out_unlock;
> +
> +	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host)) {
> +		error = vfs_fsync_range(file, pos, pos + count - 1,
> +			       (file->f_flags & __O_SYNC) ? 0 : 1);
> +	}
>  	goto out_unlock;
>  
>  out_trans_fail:
> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
> index 643faa4..4f3d664 100644
> --- a/fs/ntfs/file.c
> +++ b/fs/ntfs/file.c
> @@ -2127,12 +2127,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>  	mutex_lock(&inode->i_mutex);
>  	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
>  	mutex_unlock(&inode->i_mutex);
> -	if (ret > 0) {
> -		int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +
> +	return generic_write_sync(iocb, ret);
>  }
>  
>  /**
> diff --git a/fs/udf/file.c b/fs/udf/file.c
> index bb15771..1cdabd0 100644
> --- a/fs/udf/file.c
> +++ b/fs/udf/file.c
> @@ -155,16 +155,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	retval = __generic_file_write_iter(iocb, from);
>  	mutex_unlock(&inode->i_mutex);
>  
> -	if (retval > 0) {
> -		ssize_t err;
> -
> +	if (retval > 0)
>  		mark_inode_dirty(inode);
> -		err = generic_write_sync(file, iocb->ki_pos - retval, retval);
> -		if (err < 0)
> -			retval = err;
> -	}
> -
> -	return retval;
> +	return generic_write_sync(iocb, retval);
>  }
>  
>  long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 0655915..a8cab66 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -792,14 +792,8 @@ xfs_file_write_iter(
>  		ret = xfs_file_buffered_aio_write(iocb, from);
>  
>  	if (ret > 0) {
> -		ssize_t err;
> -
>  		XFS_STATS_ADD(xs_write_bytes, ret);
> -
> -		/* Handle various SYNC-type writes */
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> +		ret = generic_write_sync(iocb, ret);
>  	}
>  	return ret;
>  }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index eaebd99..7d0e116 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2242,13 +2242,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
>  extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
>  			   int datasync);
>  extern int vfs_fsync(struct file *file, int datasync);
> -static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> -{
> -	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
> -		return 0;
> -	return vfs_fsync_range(file, pos, pos + count - 1,
> -			       (file->f_flags & __O_SYNC) ? 0 : 1);
> -}
> +extern int generic_write_sync(struct kiocb *iocb, loff_t count);
>  extern void emergency_sync(void);
>  extern void emergency_remount(void);
>  #ifdef CONFIG_BLOCK
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 09d3af3..6107058 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2664,6 +2664,24 @@ out:
>  }
>  EXPORT_SYMBOL(__generic_file_write_iter);
>  
> +int generic_write_sync(struct kiocb *iocb, loff_t count)
> +{
> +	struct file *file = iocb->ki_filp;
> +
> +	if (count > 0 &&
> +	    ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))) {
> +		bool fdatasync = !(file->f_flags & __O_SYNC);
> +		ssize_t ret = 0;
> +
> +		ret = vfs_fsync_range(file, iocb->ki_pos - count,
> +				iocb->ki_pos - 1, fdatasync);
> +		if (ret < 0)
> +			return ret;
> +	}
> +	return count;
> +}
> +EXPORT_SYMBOL(generic_write_sync);
> +
>  /**
>   * generic_file_write_iter - write data to a file
>   * @iocb:	IO state structure
> @@ -2675,22 +2693,14 @@ EXPORT_SYMBOL(__generic_file_write_iter);
>   */
>  ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  {
> -	struct file *file = iocb->ki_filp;
> -	struct inode *inode = file->f_mapping->host;
> +	struct inode *inode = iocb->ki_filp->f_mapping->host;
>  	ssize_t ret;
>  
>  	mutex_lock(&inode->i_mutex);
>  	ret = __generic_file_write_iter(iocb, from);
>  	mutex_unlock(&inode->i_mutex);
>  
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	return ret;
> +	return generic_write_sync(iocb, ret);
>  }
>  EXPORT_SYMBOL(generic_file_write_iter);
>  
> -- 
> 1.9.1
> 
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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Re: [Linux-NTFS-Dev] [PATCH v5 6/7] fs: pass iocb to generic_write_sync

[Milosz Tanski]

On Thu, Nov 6, 2014 at 5:52 AM, Anton Altaparmakov <aia21@cam.ac.uk> wrote:
> Hi,
>
>> On 5 Nov 2014, at 23:14, Milosz Tanski <milosz@adfin.com> wrote:
>>
>> From: Christoph Hellwig <hch@lst.de>
>>
>> Clean up the generic_write_sync by just passing an iocb and a bytes
>> written / negative errno argument.  In addition to simplifying the
>> callers this also prepares for passing a per-operation O_DSYNC
>> flag.  Two callers didn't quite fit that scheme:
>>
>> - dio_complete didn't both to update ki_pos as we don't need it
>>   on a iocb that is about to be freed, so we had to add it. Additionally
>>   it also synced out written data in the error case, which has been
>>   changed to operate like the other callers.
>> - gfs2 also used generic_write_sync to implement a crude version
>>   of fallocate.  It has been switched to use an open coded variant
>>   instead.
>>
>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>> ---
>> fs/block_dev.c     |  8 +-------
>> fs/btrfs/file.c    |  7 ++-----
>> fs/cifs/file.c     |  8 +-------
>> fs/direct-io.c     |  8 ++------
>> fs/ext4/file.c     |  8 +-------
>> fs/gfs2/file.c     |  9 +++++++--
>> fs/ntfs/file.c     |  8 ++------
>> fs/udf/file.c      | 11 ++---------
>> fs/xfs/xfs_file.c  |  8 +-------
>> include/linux/fs.h |  8 +-------
>> mm/filemap.c       | 30 ++++++++++++++++++++----------
>> 11 files changed, 40 insertions(+), 73 deletions(-)
>>
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index cc9d411..c529b1c 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -1568,18 +1568,12 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
>>  */
>> ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
>> {
>> -     struct file *file = iocb->ki_filp;
>>       struct blk_plug plug;
>>       ssize_t ret;
>>
>>       blk_start_plug(&plug);
>>       ret = __generic_file_write_iter(iocb, from);
>> -     if (ret > 0) {
>> -             ssize_t err;
>> -             err = generic_write_sync(file, iocb->ki_pos - ret, ret);
>> -             if (err < 0)
>> -                     ret = err;
>> -     }
>> +     ret = generic_write_sync(iocb, ret);
>>       blk_finish_plug(&plug);
>>       return ret;
>> }
>> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
>> index a18ceab..4f4a6f7 100644
>> --- a/fs/btrfs/file.c
>> +++ b/fs/btrfs/file.c
>> @@ -1820,11 +1820,8 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
>>        */
>>       BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
>>       BTRFS_I(inode)->last_sub_trans = root->log_transid;
>> -     if (num_written > 0) {
>> -             err = generic_write_sync(file, pos, num_written);
>> -             if (err < 0)
>> -                     num_written = err;
>> -     }
>> +
>> +     num_written = generic_write_sync(iocb, num_written);
>>
>>       if (sync)
>>               atomic_dec(&BTRFS_I(inode)->sync_writers);
>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>> index c485afa..32359de 100644
>> --- a/fs/cifs/file.c
>> +++ b/fs/cifs/file.c
>> @@ -2706,13 +2706,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
>>               rc = __generic_file_write_iter(iocb, from);
>>               mutex_unlock(&inode->i_mutex);
>>
>> -             if (rc > 0) {
>> -                     ssize_t err;
>> -
>> -                     err = generic_write_sync(file, iocb->ki_pos - rc, rc);
>> -                     if (err < 0)
>> -                             rc = err;
>> -             }
>> +             rc = generic_write_sync(iocb, rc);
>>       } else {
>>               mutex_unlock(&inode->i_mutex);
>>       }
>> diff --git a/fs/direct-io.c b/fs/direct-io.c
>> index e181b6b..b72ac83 100644
>> --- a/fs/direct-io.c
>> +++ b/fs/direct-io.c
>> @@ -257,12 +257,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
>>       inode_dio_done(dio->inode);
>>       if (is_async) {
>>               if (dio->rw & WRITE) {
>> -                     int err;
>> -
>> -                     err = generic_write_sync(dio->iocb->ki_filp, offset,
>> -                                              transferred);
>> -                     if (err < 0 && ret > 0)
>> -                             ret = err;
>> +                     dio->iocb->ki_pos = offset + transferred;
>> +                     ret = generic_write_sync(dio->iocb, ret);
>>               }
>>
>>               aio_complete(dio->iocb, ret, 0);
>> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
>> index aca7b24..79b000c 100644
>> --- a/fs/ext4/file.c
>> +++ b/fs/ext4/file.c
>> @@ -175,13 +175,7 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>       ret = __generic_file_write_iter(iocb, from);
>>       mutex_unlock(&inode->i_mutex);
>>
>> -     if (ret > 0) {
>> -             ssize_t err;
>> -
>> -             err = generic_write_sync(file, iocb->ki_pos - ret, ret);
>> -             if (err < 0)
>> -                     ret = err;
>> -     }
>> +     ret = generic_write_sync(iocb, ret);
>>       if (o_direct)
>>               blk_finish_plug(&plug);
>>
>> diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
>> index 80dd44d..3fafeca 100644
>> --- a/fs/gfs2/file.c
>> +++ b/fs/gfs2/file.c
>> @@ -895,8 +895,13 @@ retry:
>>               gfs2_quota_unlock(ip);
>>       }
>>
>> -     if (error == 0)
>> -             error = generic_write_sync(file, pos, count);
>> +     if (error)
>> +             goto out_unlock;
>> +
>> +     if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host)) {
>> +             error = vfs_fsync_range(file, pos, pos + count - 1,
>> +                            (file->f_flags & __O_SYNC) ? 0 : 1);
>> +     }
>>       goto out_unlock;
>>
>> out_trans_fail:
>> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
>> index 643faa4..4f3d664 100644
>> --- a/fs/ntfs/file.c
>> +++ b/fs/ntfs/file.c
>> @@ -2127,12 +2127,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
>>       mutex_lock(&inode->i_mutex);
>>       ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
>>       mutex_unlock(&inode->i_mutex);
>> -     if (ret > 0) {
>> -             int err = generic_write_sync(file, iocb->ki_pos - ret, ret);
>> -             if (err < 0)
>> -                     ret = err;
>> -     }
>> -     return ret;
>> +
>> +     return generic_write_sync(iocb, ret);
>> }
>>
>> /**
>> diff --git a/fs/udf/file.c b/fs/udf/file.c
>> index bb15771..1cdabd0 100644
>> --- a/fs/udf/file.c
>> +++ b/fs/udf/file.c
>> @@ -155,16 +155,9 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>       retval = __generic_file_write_iter(iocb, from);
>>       mutex_unlock(&inode->i_mutex);
>>
>> -     if (retval > 0) {
>> -             ssize_t err;
>> -
>> +     if (retval > 0)
>>               mark_inode_dirty(inode);
>> -             err = generic_write_sync(file, iocb->ki_pos - retval, retval);
>> -             if (err < 0)
>> -                     retval = err;
>> -     }
>> -
>> -     return retval;
>> +     return generic_write_sync(iocb, retval);
>> }
>>
>> long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index 0655915..a8cab66 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -792,14 +792,8 @@ xfs_file_write_iter(
>>               ret = xfs_file_buffered_aio_write(iocb, from);
>>
>>       if (ret > 0) {
>> -             ssize_t err;
>> -
>>               XFS_STATS_ADD(xs_write_bytes, ret);
>> -
>> -             /* Handle various SYNC-type writes */
>> -             err = generic_write_sync(file, iocb->ki_pos - ret, ret);
>> -             if (err < 0)
>> -                     ret = err;
>> +             ret = generic_write_sync(iocb, ret);
>>       }
>>       return ret;
>> }
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index eaebd99..7d0e116 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -2242,13 +2242,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
>> extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
>>                          int datasync);
>> extern int vfs_fsync(struct file *file, int datasync);
>> -static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
>> -{
>> -     if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
>> -             return 0;
>> -     return vfs_fsync_range(file, pos, pos + count - 1,
>> -                            (file->f_flags & __O_SYNC) ? 0 : 1);
>> -}
>> +extern int generic_write_sync(struct kiocb *iocb, loff_t count);
>> extern void emergency_sync(void);
>> extern void emergency_remount(void);
>> #ifdef CONFIG_BLOCK
>> diff --git a/mm/filemap.c b/mm/filemap.c
>> index 09d3af3..6107058 100644
>> --- a/mm/filemap.c
>> +++ b/mm/filemap.c
>> @@ -2664,6 +2664,24 @@ out:
>> }
>> EXPORT_SYMBOL(__generic_file_write_iter);
>>
>> +int generic_write_sync(struct kiocb *iocb, loff_t count)
>> +{
>> +     struct file *file = iocb->ki_filp;
>> +
>> +     if (count > 0 &&
>> +         ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))) {
>> +             bool fdatasync = !(file->f_flags & __O_SYNC);
>> +             ssize_t ret = 0;
>
> That "= 0" is pointless.  "ret" is overwritten unconditionally on the following line...

I have fixed this change; it will be in the next patch series / pull
request. The branch for the pull is at:
https://bitbucket.org/adfin/linux-fs.git  read_call_6

>
> Other than that the NTFS bits are:
>
> Acked-by: Anton Altaparmakov <anton@tuxera.com>
>
> Best regards,
>
>         Anton
>
>> +
>> +             ret = vfs_fsync_range(file, iocb->ki_pos - count,
>> +                             iocb->ki_pos - 1, fdatasync);
>> +             if (ret < 0)
>> +                     return ret;
>> +     }
>> +     return count;
>> +}
>> +EXPORT_SYMBOL(generic_write_sync);
>> +
>> /**
>>  * generic_file_write_iter - write data to a file
>>  * @iocb:     IO state structure
>> @@ -2675,22 +2693,14 @@ EXPORT_SYMBOL(__generic_file_write_iter);
>>  */
>> ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>> {
>> -     struct file *file = iocb->ki_filp;
>> -     struct inode *inode = file->f_mapping->host;
>> +     struct inode *inode = iocb->ki_filp->f_mapping->host;
>>       ssize_t ret;
>>
>>       mutex_lock(&inode->i_mutex);
>>       ret = __generic_file_write_iter(iocb, from);
>>       mutex_unlock(&inode->i_mutex);
>>
>> -     if (ret > 0) {
>> -             ssize_t err;
>> -
>> -             err = generic_write_sync(file, iocb->ki_pos - ret, ret);
>> -             if (err < 0)
>> -                     ret = err;
>> -     }
>> -     return ret;
>> +     return generic_write_sync(iocb, ret);
>> }
>> EXPORT_SYMBOL(generic_file_write_iter);
>
> --
> Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
> University of Cambridge Information Services, Roger Needham Building
> 7 JJ Thomson Avenue, Cambridge, CB3 0RB, UK
>



-- 
Milosz Tanski
CTO
16 East 34th Street, 15th floor
New York, NY 10016

p: 646-253-9055
e: milosz@adfin.com

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Re: [PATCH v5 4/7] vfs: RWF_NONBLOCK flag for preadv2

[Sage Weil]

On Wed, 5 Nov 2014, Milosz Tanski wrote:
> generic_file_read_iter() supports a new flag RWF_NONBLOCK which says that we
> only want to read the data if it's already in the page cache.
> 
> Additionally, there are a few filesystems that we have to specifically
> bail early if RWF_NONBLOCK because the op would block. Christoph Hellwig
> contributed this code.
> 
> Signed-off-by: Milosz Tanski <milosz@adfin.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>

Ceph bits

Acked-by: Sage Weil <sage@redhat.com>


> ---
>  fs/ceph/file.c     |  2 ++
>  fs/cifs/file.c     |  6 ++++++
>  fs/nfs/file.c      |  5 ++++-
>  fs/ocfs2/file.c    |  6 ++++++
>  fs/pipe.c          |  3 ++-
>  fs/read_write.c    | 38 +++++++++++++++++++++++++-------------
>  fs/xfs/xfs_file.c  |  4 ++++
>  include/linux/fs.h |  3 +++
>  mm/filemap.c       | 18 ++++++++++++++++++
>  mm/shmem.c         |  4 ++++
>  10 files changed, 74 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index d7e0da8..b798b5c 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -822,6 +822,8 @@ again:
>  	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
>  	    (iocb->ki_filp->f_flags & O_DIRECT) ||
>  	    (fi->flags & CEPH_F_SYNC)) {
> +		if (iocb->ki_rwflags & O_NONBLOCK)
> +			return -EAGAIN;
>  
>  		dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n",
>  		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 3e4d00a..c485afa 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3005,6 +3005,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
>  	struct cifs_readdata *rdata, *tmp;
>  	struct list_head rdata_list;
>  
> +	if (iocb->ki_rwflags & RWF_NONBLOCK)
> +		return -EAGAIN;
> +
>  	len = iov_iter_count(to);
>  	if (!len)
>  		return 0;
> @@ -3123,6 +3126,9 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
>  	    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
>  		return generic_file_read_iter(iocb, to);
>  
> +	if (iocb->ki_rwflags & RWF_NONBLOCK)
> +		return -EAGAIN;
> +
>  	/*
>  	 * We need to hold the sem to be sure nobody modifies lock list
>  	 * with a brlock that prevents reading.
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index 2ab6f00..aa9046f 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -171,8 +171,11 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
>  	struct inode *inode = file_inode(iocb->ki_filp);
>  	ssize_t result;
>  
> -	if (iocb->ki_filp->f_flags & O_DIRECT)
> +	if (iocb->ki_filp->f_flags & O_DIRECT) {
> +		if (iocb->ki_rwflags & O_NONBLOCK)
> +			return -EAGAIN;
>  		return nfs_file_direct_read(iocb, to, iocb->ki_pos);
> +	}
>  
>  	dprintk("NFS: read(%pD2, %zu@%lu)\n",
>  		iocb->ki_filp,
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 324dc93..bb66ca4 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2472,6 +2472,12 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
>  			filp->f_path.dentry->d_name.name,
>  			to->nr_segs);	/* GRRRRR */
>  
> +	/*
> +	 * No non-blocking reads for ocfs2 for now.  Might be doable with
> +	 * non-blocking cluster lock helpers.
> +	 */
> +	if (iocb->ki_rwflags & RWF_NONBLOCK)
> +		return -EAGAIN;
>  
>  	if (!inode) {
>  		ret = -EINVAL;
> diff --git a/fs/pipe.c b/fs/pipe.c
> index 21981e5..212bf68 100644
> --- a/fs/pipe.c
> +++ b/fs/pipe.c
> @@ -302,7 +302,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
>  			 */
>  			if (ret)
>  				break;
> -			if (filp->f_flags & O_NONBLOCK) {
> +			if ((filp->f_flags & O_NONBLOCK) ||
> +			    (iocb->ki_rwflags & RWF_NONBLOCK)) {
>  				ret = -EAGAIN;
>  				break;
>  			}
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 907735c..cba7d4c 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -835,14 +835,19 @@ static ssize_t do_readv_writev(int type, struct file *file,
>  		file_start_write(file);
>  	}
>  
> -	if (iter_fn)
> +	if (iter_fn) {
>  		ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
>  						pos, iter_fn, flags);
> -	else if (fnv)
> -		ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
> -						pos, fnv);
> -	else
> -		ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
> +	} else {
> +		if (type == READ && (flags & RWF_NONBLOCK))
> +			return -EAGAIN;
> +
> +		if (fnv)
> +			ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
> +							pos, fnv);
> +		else
> +			ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
> +	}
>  
>  	if (type != READ)
>  		file_end_write(file);
> @@ -866,8 +871,10 @@ ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
>  		return -EBADF;
>  	if (!(file->f_mode & FMODE_CAN_READ))
>  		return -EINVAL;
> -	if (flags & ~0)
> +	if (flags & ~RWF_NONBLOCK)
>  		return -EINVAL;
> +	if ((file->f_flags & O_DIRECT) && (flags & RWF_NONBLOCK))
> +		return -EAGAIN;
>  
>  	return do_readv_writev(READ, file, vec, vlen, pos, flags);
>  }
> @@ -1069,14 +1076,19 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
>  		file_start_write(file);
>  	}
>  
> -	if (iter_fn)
> +	if (iter_fn) {
>  		ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
>  						pos, iter_fn, flags);
> -	else if (fnv)
> -		ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
> -						pos, fnv);
> -	else
> -		ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
> +	} else {
> +		if (type == READ && (flags & RWF_NONBLOCK))
> +			return -EAGAIN;
> +
> +		if (fnv)
> +			ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
> +							pos, fnv);
> +		else
> +			ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
> +	}
>  
>  	if (type != READ)
>  		file_end_write(file);
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index eb596b4..b1f6334 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -246,6 +246,10 @@ xfs_file_read_iter(
>  
>  	XFS_STATS_INC(xs_read_calls);
>  
> +	/* XXX: need a non-blocking iolock helper, shouldn't be too hard */
> +	if (iocb->ki_rwflags & RWF_NONBLOCK)
> +		return -EAGAIN;
> +
>  	if (unlikely(file->f_flags & O_DIRECT))
>  		ioflags |= XFS_IO_ISDIRECT;
>  	if (file->f_mode & FMODE_NOCMTIME)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 9ed5711..eaebd99 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1459,6 +1459,9 @@ struct block_device_operations;
>  #define HAVE_COMPAT_IOCTL 1
>  #define HAVE_UNLOCKED_IOCTL 1
>  
> +/* These flags are used for the readv/writev syscalls with flags. */
> +#define RWF_NONBLOCK 0x00000001
> +
>  struct iov_iter;
>  
>  struct file_operations {
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 530c263..09d3af3 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1494,6 +1494,8 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
>  find_page:
>  		page = find_get_page(mapping, index);
>  		if (!page) {
> +			if (flags & RWF_NONBLOCK)
> +				goto would_block;
>  			page_cache_sync_readahead(mapping,
>  					ra, filp,
>  					index, last_index - index);
> @@ -1585,6 +1587,11 @@ page_ok:
>  		continue;
>  
>  page_not_up_to_date:
> +		if (flags & RWF_NONBLOCK) {
> +			page_cache_release(page);
> +			goto would_block;
> +		}
> +
>  		/* Get exclusive access to the page ... */
>  		error = lock_page_killable(page);
>  		if (unlikely(error))
> @@ -1604,6 +1611,12 @@ page_not_up_to_date_locked:
>  			goto page_ok;
>  		}
>  
> +		if (flags & RWF_NONBLOCK) {
> +			unlock_page(page);
> +			page_cache_release(page);
> +			goto would_block;
> +		}
> +
>  readpage:
>  		/*
>  		 * A previous I/O error may have been due to temporary
> @@ -1674,6 +1687,8 @@ no_cached_page:
>  		goto readpage;
>  	}
>  
> +would_block:
> +	error = -EAGAIN;
>  out:
>  	ra->prev_pos = prev_index;
>  	ra->prev_pos <<= PAGE_CACHE_SHIFT;
> @@ -1707,6 +1722,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
>  		size_t count = iov_iter_count(iter);
>  		loff_t size;
>  
> +		if (iocb->ki_rwflags & RWF_NONBLOCK)
> +			return -EAGAIN;
> +
>  		if (!count)
>  			goto out; /* skip atime */
>  		size = i_size_read(inode);
> diff --git a/mm/shmem.c b/mm/shmem.c
> index cd6fc75..5c30f04 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1531,6 +1531,10 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  	ssize_t retval = 0;
>  	loff_t *ppos = &iocb->ki_pos;
>  
> +	/* XXX: should be easily supportable */
> +	if (iocb->ki_rwflags & RWF_NONBLOCK)
> +		return -EAGAIN;
> +
>  	/*
>  	 * Might this read be for a stacking filesystem?  Then when reading
>  	 * holes of a sparse file, we actually need to allocate those pages,
> -- 
> 1.9.1
> 
> --
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> 
> 

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