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Commit e4dd9de3 authored by Jan Kara's avatar Jan Kara
Browse files

vfs: Export __generic_file_aio_write() and add some comments 



Rename __generic_file_aio_write_nolock() to __generic_file_aio_write(), add
comments to write helpers explaining how they should be used and export
__generic_file_aio_write() since it will be used by some filesystems.

CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent d3bccb6f

include/linux/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -2204,6 +2204,8 @@ extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *); 
extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);

int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);

extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);

extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,

		loff_t *);

extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);

extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct iovec *,

		unsigned long, loff_t);

mm/filemap.c

+50 −7
Original line number Diff line number Diff line
@@ -2368,8 +2368,26 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, 
}

EXPORT_SYMBOL(generic_file_buffered_write);



static ssize_t

__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,

/**

 * __generic_file_aio_write - write data to a file

 * @iocb:	IO state structure (file, offset, etc.)

 * @iov:	vector with data to write

 * @nr_segs:	number of segments in the vector

 * @ppos:	position where to write

 *

 * This function does all the work needed for actually writing data to a

 * file. It does all basic checks, removes SUID from the file, updates

 * modification times and calls proper subroutines depending on whether we

 * do direct IO or a standard buffered write.

 *

 * It expects i_mutex to be grabbed unless we work on a block device or similar

 * object which does not need locking at all.

 *

 * This function does *not* take care of syncing data in case of O_SYNC write.

 * A caller has to handle it. This is mainly due to the fact that we want to

 * avoid syncing under i_mutex.

 */

ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,

				 unsigned long nr_segs, loff_t *ppos)

{

	struct file *file = iocb->ki_filp;
@@ -2467,7 +2485,23 @@ out: 
	current->backing_dev_info = NULL;

	return written ? written : err;

}

EXPORT_SYMBOL(__generic_file_aio_write);





/**

 * generic_file_aio_write_nolock - write data, usually to a device

 * @iocb:	IO state structure

 * @iov:	vector with data to write

 * @nr_segs:	number of segments in the vector

 * @pos:	position in file where to write

 *

 * This is a wrapper around __generic_file_aio_write() which takes care of

 * syncing the file in case of O_SYNC file. It does not take i_mutex for the

 * write itself but may do so during syncing. It is meant for users like block

 * devices which do not need i_mutex during write. If your filesystem needs to

 * do a write but already holds i_mutex, use __generic_file_aio_write()

 * directly and then sync the file like generic_file_aio_write().

 */

ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,

		const struct iovec *iov, unsigned long nr_segs, loff_t pos)

{
@@ -2478,8 +2512,7 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, 


	BUG_ON(iocb->ki_pos != pos);



	ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,

			&iocb->ki_pos);

	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);



	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {

		ssize_t err;
@@ -2492,6 +2525,17 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb, 
}

EXPORT_SYMBOL(generic_file_aio_write_nolock);



/**

 * generic_file_aio_write - write data to a file

 * @iocb:	IO state structure

 * @iov:	vector with data to write

 * @nr_segs:	number of segments in the vector

 * @pos:	position in file where to write

 *

 * This is a wrapper around __generic_file_aio_write() to be used by most

 * filesystems. It takes care of syncing the file in case of O_SYNC file

 * and acquires i_mutex as needed.

 */

ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,

		unsigned long nr_segs, loff_t pos)

{
@@ -2503,8 +2547,7 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, 
	BUG_ON(iocb->ki_pos != pos);



	mutex_lock(&inode->i_mutex);

	ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,

			&iocb->ki_pos);

	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);

	mutex_unlock(&inode->i_mutex);



	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {