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Commit 0ed3b0d4 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Darrick J. Wong
Browse files

vfs: Add iomap_seek_hole and iomap_seek_data helpers 



Filesystems can use this for implementing lseek SEEK_HOLE / SEEK_DATA
support via iomap.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
[hch: split functions, coding style cleanups]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent 334fd34d

fs/iomap.c

+94 −0
Original line number Diff line number Diff line
@@ -584,6 +584,100 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, 
}

EXPORT_SYMBOL_GPL(iomap_fiemap);



static loff_t

iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,

		      void *data, struct iomap *iomap)

{

	switch (iomap->type) {

	case IOMAP_UNWRITTEN:

		offset = page_cache_seek_hole_data(inode, offset, length,

						   SEEK_HOLE);

		if (offset < 0)

			return length;

		/* fall through */

	case IOMAP_HOLE:

		*(loff_t *)data = offset;

		return 0;

	default:

		return length;

	}

}



loff_t

iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)

{

	loff_t size = i_size_read(inode);

	loff_t length = size - offset;

	loff_t ret;



	/* Nothing to be found beyond the end of the file. */

	if (offset >= size)

		return -ENXIO;



	while (length > 0) {

		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,

				  &offset, iomap_seek_hole_actor);

		if (ret < 0)

			return ret;

		if (ret == 0)

			break;



		offset += ret;

		length -= ret;

	}



	return offset;

}

EXPORT_SYMBOL_GPL(iomap_seek_hole);



static loff_t

iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length,

		      void *data, struct iomap *iomap)

{

	switch (iomap->type) {

	case IOMAP_HOLE:

		return length;

	case IOMAP_UNWRITTEN:

		offset = page_cache_seek_hole_data(inode, offset, length,

						   SEEK_DATA);

		if (offset < 0)

			return length;

		/*FALLTHRU*/

	default:

		*(loff_t *)data = offset;

		return 0;

	}

}



loff_t

iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops)

{

	loff_t size = i_size_read(inode);

	loff_t length = size - offset;

	loff_t ret;



	/* Nothing to be found beyond the end of the file. */

	if (offset >= size)

		return -ENXIO;



	while (length > 0) {

		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,

				  &offset, iomap_seek_data_actor);

		if (ret < 0)

			return ret;

		if (ret == 0)

			break;



		offset += ret;

		length -= ret;

	}



	if (length <= 0)

		return -ENXIO;

	return offset;

}

EXPORT_SYMBOL_GPL(iomap_seek_data);



/*

 * Private flags for iomap_dio, must not overlap with the public ones in

 * iomap.h:

include/linux/iomap.h

+4 −0
Original line number Diff line number Diff line
@@ -83,6 +83,10 @@ int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, 
int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops);

int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

		loff_t start, loff_t len, const struct iomap_ops *ops);

loff_t iomap_seek_hole(struct inode *inode, loff_t offset,

		const struct iomap_ops *ops);

loff_t iomap_seek_data(struct inode *inode, loff_t offset,

		const struct iomap_ops *ops);



/*

 * Flags for direct I/O ->end_io: