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Commit 967bcc91 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: iomap direct I/O support 



The page unmapping previously done in gfs2_direct_IO is now done
generically in iomap_dio_rw.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarBob Peterson <rpeterso@redhat.com>
parent bcfe9413

fs/gfs2/aops.c

+2 −98
Original line number Diff line number Diff line
@@ -84,12 +84,6 @@ static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock, 
	return 0;

}



static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,

				 struct buffer_head *bh_result, int create)

{

	return gfs2_block_map(inode, lblock, bh_result, 0);

}



/**

 * gfs2_writepage_common - Common bits of writepage

 * @page: The page to be written
@@ -1024,96 +1018,6 @@ static void gfs2_invalidatepage(struct page *page, unsigned int offset, 
		try_to_release_page(page, 0);

}



/**

 * gfs2_ok_for_dio - check that dio is valid on this file

 * @ip: The inode

 * @offset: The offset at which we are reading or writing

 *

 * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)

 *          1 (to accept the i/o request)

 */

static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)

{

	/*

	 * Should we return an error here? I can't see that O_DIRECT for

	 * a stuffed file makes any sense. For now we'll silently fall

	 * back to buffered I/O

	 */

	if (gfs2_is_stuffed(ip))

		return 0;



	if (offset >= i_size_read(&ip->i_inode))

		return 0;

	return 1;

}







static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)

{

	struct file *file = iocb->ki_filp;

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

	struct address_space *mapping = inode->i_mapping;

	struct gfs2_inode *ip = GFS2_I(inode);

	loff_t offset = iocb->ki_pos;

	struct gfs2_holder gh;

	int rv;



	/*

	 * Deferred lock, even if its a write, since we do no allocation

	 * on this path. All we need change is atime, and this lock mode

	 * ensures that other nodes have flushed their buffered read caches

	 * (i.e. their page cache entries for this inode). We do not,

	 * unfortunately have the option of only flushing a range like

	 * the VFS does.

	 */

	gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);

	rv = gfs2_glock_nq(&gh);

	if (rv)

		goto out_uninit;

	rv = gfs2_ok_for_dio(ip, offset);

	if (rv != 1)

		goto out; /* dio not valid, fall back to buffered i/o */



	/*

	 * Now since we are holding a deferred (CW) lock at this point, you

	 * might be wondering why this is ever needed. There is a case however

	 * where we've granted a deferred local lock against a cached exclusive

	 * glock. That is ok provided all granted local locks are deferred, but

	 * it also means that it is possible to encounter pages which are

	 * cached and possibly also mapped. So here we check for that and sort

	 * them out ahead of the dio. The glock state machine will take care of

	 * everything else.

	 *

	 * If in fact the cached glock state (gl->gl_state) is deferred (CW) in

	 * the first place, mapping->nr_pages will always be zero.

	 */

	if (mapping->nrpages) {

		loff_t lstart = offset & ~(PAGE_SIZE - 1);

		loff_t len = iov_iter_count(iter);

		loff_t end = PAGE_ALIGN(offset + len) - 1;



		rv = 0;

		if (len == 0)

			goto out;

		if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))

			unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);

		rv = filemap_write_and_wait_range(mapping, lstart, end);

		if (rv)

			goto out;

		if (iov_iter_rw(iter) == WRITE)

			truncate_inode_pages_range(mapping, lstart, end);

	}



	rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,

				  gfs2_get_block_direct, NULL, NULL, 0);

out:

	gfs2_glock_dq(&gh);

out_uninit:

	gfs2_holder_uninit(&gh);

	return rv;

}



/**

 * gfs2_releasepage - free the metadata associated with a page

 * @page: the page that's being released
@@ -1194,7 +1098,7 @@ static const struct address_space_operations gfs2_writeback_aops = { 
	.bmap = gfs2_bmap,

	.invalidatepage = gfs2_invalidatepage,

	.releasepage = gfs2_releasepage,

	.direct_IO = gfs2_direct_IO,

	.direct_IO = noop_direct_IO,

	.migratepage = buffer_migrate_page,

	.is_partially_uptodate = block_is_partially_uptodate,

	.error_remove_page = generic_error_remove_page,
@@ -1211,7 +1115,7 @@ static const struct address_space_operations gfs2_ordered_aops = { 
	.bmap = gfs2_bmap,

	.invalidatepage = gfs2_invalidatepage,

	.releasepage = gfs2_releasepage,

	.direct_IO = gfs2_direct_IO,

	.direct_IO = noop_direct_IO,

	.migratepage = buffer_migrate_page,

	.is_partially_uptodate = block_is_partially_uptodate,

	.error_remove_page = generic_error_remove_page,

fs/gfs2/bmap.c

+12 −2
Original line number Diff line number Diff line
@@ -915,6 +915,9 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length, 
	} else if (flags & IOMAP_WRITE) {

		u64 alloc_size;



		if (flags & IOMAP_DIRECT)

			goto out;  /* (see gfs2_file_direct_write) */



		len = gfs2_alloc_size(inode, mp, len);

		alloc_size = len << inode->i_blkbits;

		if (alloc_size < iomap->length)
@@ -1082,11 +1085,18 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length, 
	int ret;



	trace_gfs2_iomap_start(ip, pos, length, flags);

	if (flags & IOMAP_WRITE) {

	if ((flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)) {

		ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap);

	} else {

		ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);

		release_metapath(&mp);

		/*

		 * Silently fall back to buffered I/O for stuffed files or if

		 * we've hot a hole (see gfs2_file_direct_write).

		 */

		if ((flags & IOMAP_WRITE) && (flags & IOMAP_DIRECT) &&

		    iomap->type != IOMAP_MAPPED)

			ret = -ENOTBLK;

	}

	trace_gfs2_iomap_end(ip, iomap, ret);

	return ret;
@@ -1100,7 +1110,7 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length, 
	struct gfs2_trans *tr = current->journal_info;

	struct buffer_head *dibh = iomap->private;



	if (!(flags & IOMAP_WRITE))

	if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)

		goto out;



	if (iomap->type != IOMAP_INLINE) {

fs/gfs2/file.c

+122 −10
Original line number Diff line number Diff line
@@ -690,6 +690,85 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end, 
	return ret ? ret : ret1;

}



static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to)

{

	struct file *file = iocb->ki_filp;

	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);

	size_t count = iov_iter_count(to);

	struct gfs2_holder gh;

	ssize_t ret;



	if (!count)

		return 0; /* skip atime */



	gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);

	ret = gfs2_glock_nq(&gh);

	if (ret)

		goto out_uninit;



	/* fall back to buffered I/O for stuffed files */

	ret = -ENOTBLK;

	if (gfs2_is_stuffed(ip))

		goto out;



	ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL);



out:

	gfs2_glock_dq(&gh);

out_uninit:

	gfs2_holder_uninit(&gh);

	return ret;

}



static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;

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

	struct gfs2_inode *ip = GFS2_I(inode);

	size_t len = iov_iter_count(from);

	loff_t offset = iocb->ki_pos;

	struct gfs2_holder gh;

	ssize_t ret;



	/*

	 * Deferred lock, even if its a write, since we do no allocation on

	 * this path. All we need to change is the atime, and this lock mode

	 * ensures that other nodes have flushed their buffered read caches

	 * (i.e. their page cache entries for this inode). We do not,

	 * unfortunately, have the option of only flushing a range like the

	 * VFS does.

	 */

	gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);

	ret = gfs2_glock_nq(&gh);

	if (ret)

		goto out_uninit;



	/* Silently fall back to buffered I/O when writing beyond EOF */

	if (offset + len > i_size_read(&ip->i_inode))

		goto out;



	ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL);



out:

	gfs2_glock_dq(&gh);

out_uninit:

	gfs2_holder_uninit(&gh);

	return ret;

}



static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	ssize_t ret;



	if (iocb->ki_flags & IOCB_DIRECT) {

		ret = gfs2_file_direct_read(iocb, to);

		if (likely(ret != -ENOTBLK))

			return ret;

		iocb->ki_flags &= ~IOCB_DIRECT;

	}

	return generic_file_read_iter(iocb, to);

}



/**

 * gfs2_file_write_iter - Perform a write to a file

 * @iocb: The io context
@@ -707,7 +786,7 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	struct file *file = iocb->ki_filp;

	struct inode *inode = file_inode(file);

	struct gfs2_inode *ip = GFS2_I(inode);

	ssize_t ret;

	ssize_t written = 0, ret;



	ret = gfs2_rsqa_alloc(ip);

	if (ret)
@@ -724,9 +803,6 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
		gfs2_glock_dq_uninit(&gh);

	}



	if (iocb->ki_flags & IOCB_DIRECT)

		return generic_file_write_iter(iocb, from);



	inode_lock(inode);

	ret = generic_write_checks(iocb, from);

	if (ret <= 0)
@@ -743,19 +819,55 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	if (ret)

		goto out2;



	if (iocb->ki_flags & IOCB_DIRECT) {

		struct address_space *mapping = file->f_mapping;

		loff_t pos, endbyte;

		ssize_t buffered;



		written = gfs2_file_direct_write(iocb, from);

		if (written < 0 || !iov_iter_count(from))

			goto out2;



		ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);

		if (unlikely(ret < 0))

			goto out2;

		buffered = ret;



		/*

		 * We need to ensure that the page cache pages are written to

		 * disk and invalidated to preserve the expected O_DIRECT

		 * semantics.

		 */

		pos = iocb->ki_pos;

		endbyte = pos + buffered - 1;

		ret = filemap_write_and_wait_range(mapping, pos, endbyte);

		if (!ret) {

			iocb->ki_pos += buffered;

			written += buffered;

			invalidate_mapping_pages(mapping,

						 pos >> PAGE_SHIFT,

						 endbyte >> PAGE_SHIFT);

		} else {

			/*

			 * We don't know how much we wrote, so just return

			 * the number of bytes which were direct-written

			 */

		}

	} else {

		ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);

		if (likely(ret > 0))

			iocb->ki_pos += ret;

	}



out2:

	current->backing_dev_info = NULL;

out:

	inode_unlock(inode);

	if (likely(ret > 0)) {

		iocb->ki_pos += ret;



		/* Handle various SYNC-type writes */

		ret = generic_write_sync(iocb, ret);

	}

	return ret;

	return written ? written : ret;

}



static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
@@ -1157,7 +1269,7 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl) 


const struct file_operations gfs2_file_fops = {

	.llseek		= gfs2_llseek,

	.read_iter	= generic_file_read_iter,

	.read_iter	= gfs2_file_read_iter,

	.write_iter	= gfs2_file_write_iter,

	.unlocked_ioctl	= gfs2_ioctl,

	.mmap		= gfs2_mmap,
@@ -1187,7 +1299,7 @@ const struct file_operations gfs2_dir_fops = { 


const struct file_operations gfs2_file_fops_nolock = {

	.llseek		= gfs2_llseek,

	.read_iter	= generic_file_read_iter,

	.read_iter	= gfs2_file_read_iter,

	.write_iter	= gfs2_file_write_iter,

	.unlocked_ioctl	= gfs2_ioctl,

	.mmap		= gfs2_mmap,