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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: Evgeniy Polyakov <zbr@ioremap.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2009-08-17 18:10:06 +02:00
parent d3bccb6f4b
commit e4dd9de3c6
2 changed files with 52 additions and 7 deletions
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2
include/linux/fs.h
View File

@ -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);

57
mm/filemap.c
View File

@ -2368,9 +2368,27 @@ 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,
unsigned long nr_segs, loff_t *ppos)
/**
* __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;
struct address_space * mapping = file->f_mapping;
@ -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))) {