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Commit 148f948b authored by Jan Kara's avatar Jan Kara
Browse files

vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode 



Introduce new function for generic inode syncing (vfs_fsync_range) and use
it from fsync() path. Introduce also new helper for syncing after a sync
write (generic_write_sync) using the generic function.

Use these new helpers for syncing from generic VFS functions. This makes
O_SYNC writes to block devices acquire i_mutex for syncing. If we really
care about this, we can make block_fsync() drop the i_mutex and reacquire
it before it returns.

CC: Evgeniy Polyakov <zbr@ioremap.net>
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Acked-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent eef99380

fs/splice.c

+6 −16
Original line number Diff line number Diff line
@@ -976,25 +976,15 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 


	if (ret > 0) {

		unsigned long nr_pages;



		*ppos += ret;

		nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;



		/*

		 * If file or inode is SYNC and we actually wrote some data,

		 * sync it.

		 */

		if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {

		int err;



			mutex_lock(&inode->i_mutex);

			err = generic_osync_inode(inode, mapping,

						  OSYNC_METADATA|OSYNC_DATA);

			mutex_unlock(&inode->i_mutex);

		nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;



		err = generic_write_sync(out, *ppos, ret);

		if (err)

			ret = err;

		}

		else

			*ppos += ret;

		balance_dirty_pages_ratelimited_nr(mapping, nr_pages);

	}

fs/sync.c

+48 −7
Original line number Diff line number Diff line
@@ -178,19 +178,23 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 
}



/**

 * vfs_fsync - perform a fsync or fdatasync on a file

 * vfs_fsync_range - helper to sync a range of data & metadata to disk

 * @file:		file to sync

 * @dentry:		dentry of @file

 * @data:		only perform a fdatasync operation

 * @start:		offset in bytes of the beginning of data range to sync

 * @end:		offset in bytes of the end of data range (inclusive)

 * @datasync:		perform only datasync

 *

 * Write back data and metadata for @file to disk.  If @datasync is

 * set only metadata needed to access modified file data is written.

 * Write back data in range @start..@end and metadata for @file to disk.  If

 * @datasync is set only metadata needed to access modified file data is

 * written.

 *

 * In case this function is called from nfsd @file may be %NULL and

 * only @dentry is set.  This can only happen when the filesystem

 * implements the export_operations API.

 */

int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)

int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start,

		    loff_t end, int datasync)

{

	const struct file_operations *fop;

	struct address_space *mapping;
@@ -214,7 +218,7 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) 
		goto out;

	}



	ret = filemap_fdatawrite(mapping);

	ret = filemap_fdatawrite_range(mapping, start, end);



	/*

	 * We need to protect against concurrent writers, which could cause
@@ -225,12 +229,32 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) 
	if (!ret)

		ret = err;

	mutex_unlock(&mapping->host->i_mutex);

	err = filemap_fdatawait(mapping);



	err = filemap_fdatawait_range(mapping, start, end);

	if (!ret)

		ret = err;

out:

	return ret;

}

EXPORT_SYMBOL(vfs_fsync_range);



/**

 * vfs_fsync - perform a fsync or fdatasync on a file

 * @file:		file to sync

 * @dentry:		dentry of @file

 * @datasync:		only perform a fdatasync operation

 *

 * Write back data and metadata for @file to disk.  If @datasync is

 * set only metadata needed to access modified file data is written.

 *

 * In case this function is called from nfsd @file may be %NULL and

 * only @dentry is set.  This can only happen when the filesystem

 * implements the export_operations API.

 */

int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)

{

	return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync);

}

EXPORT_SYMBOL(vfs_fsync);



static int do_fsync(unsigned int fd, int datasync)
@@ -256,6 +280,23 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 
	return do_fsync(fd, 1);

}



/**

 * generic_write_sync - perform syncing after a write if file / inode is sync

 * @file:	file to which the write happened

 * @pos:	offset where the write started

 * @count:	length of the write

 *

 * This is just a simple wrapper about our general syncing function.

 */

int generic_write_sync(struct file *file, loff_t pos, loff_t count)

{

	if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))

		return 0;

	return vfs_fsync_range(file, file->f_path.dentry, pos,

			       pos + count - 1, 1);

}

EXPORT_SYMBOL(generic_write_sync);



/*

 * sys_sync_file_range() permits finely controlled syncing over a segment of

 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -2098,7 +2098,10 @@ extern int __filemap_fdatawrite_range(struct address_space *mapping, 
extern int filemap_fdatawrite_range(struct address_space *mapping,

				loff_t start, loff_t end);



extern int vfs_fsync_range(struct file *file, struct dentry *dentry,

			   loff_t start, loff_t end, int datasync);

extern int vfs_fsync(struct file *file, struct dentry *dentry, int datasync);

extern int generic_write_sync(struct file *file, loff_t pos, loff_t count);

extern void sync_supers(void);

extern void emergency_sync(void);

extern void emergency_remount(void);

mm/filemap.c

+4 −7
Original line number Diff line number Diff line
@@ -39,11 +39,10 @@ 
/*

 * FIXME: remove all knowledge of the buffer layer from the core VM

 */

#include <linux/buffer_head.h> /* for generic_osync_inode */

#include <linux/buffer_head.h> /* for try_to_free_buffers */



#include <asm/mman.h>





/*

 * Shared mappings implemented 30.11.1994. It's not fully working yet,

 * though.
@@ -2477,8 +2476,7 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, 
		unsigned long nr_segs, loff_t pos)

{

	struct file *file = iocb->ki_filp;

	struct address_space *mapping = file->f_mapping;

	struct inode *inode = mapping->host;

	struct inode *inode = file->f_mapping->host;

	ssize_t ret;



	BUG_ON(iocb->ki_pos != pos);
@@ -2487,11 +2485,10 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov, 
	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);

	mutex_unlock(&inode->i_mutex);



	if ((ret > 0 || ret == -EIOCBQUEUED) &&

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

	if (ret > 0 || ret == -EIOCBQUEUED) {

		ssize_t err;



		err = sync_page_range(inode, mapping, pos, ret);

		err = generic_write_sync(file, pos, ret);

		if (err < 0 && ret > 0)

			ret = err;

	}