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Commit 56a17898 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

iomap: move the SEEK_HOLE code into a separate file 



Move the SEEK_HOLE/SEEK_DATA code into a separate file so that we can
group related functions in a single file instead of having a single
enormous source file.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 5157fb8f

fs/iomap.c

+0 −201
Original line number Diff line number Diff line
@@ -1149,207 +1149,6 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) 
}

EXPORT_SYMBOL_GPL(iomap_page_mkwrite);



/*

 * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.

 * Returns true if found and updates @lastoff to the offset in file.

 */

static bool

page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,

		int whence)

{

	const struct address_space_operations *ops = inode->i_mapping->a_ops;

	unsigned int bsize = i_blocksize(inode), off;

	bool seek_data = whence == SEEK_DATA;

	loff_t poff = page_offset(page);



	if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))

		return false;



	if (*lastoff < poff) {

		/*

		 * Last offset smaller than the start of the page means we found

		 * a hole:

		 */

		if (whence == SEEK_HOLE)

			return true;

		*lastoff = poff;

	}



	/*

	 * Just check the page unless we can and should check block ranges:

	 */

	if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)

		return PageUptodate(page) == seek_data;



	lock_page(page);

	if (unlikely(page->mapping != inode->i_mapping))

		goto out_unlock_not_found;



	for (off = 0; off < PAGE_SIZE; off += bsize) {

		if (offset_in_page(*lastoff) >= off + bsize)

			continue;

		if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {

			unlock_page(page);

			return true;

		}

		*lastoff = poff + off + bsize;

	}



out_unlock_not_found:

	unlock_page(page);

	return false;

}



/*

 * Seek for SEEK_DATA / SEEK_HOLE in the page cache.

 *

 * Within unwritten extents, the page cache determines which parts are holes

 * and which are data: uptodate buffer heads count as data; everything else

 * counts as a hole.

 *

 * Returns the resulting offset on successs, and -ENOENT otherwise.

 */

static loff_t

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

		int whence)

{

	pgoff_t index = offset >> PAGE_SHIFT;

	pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);

	loff_t lastoff = offset;

	struct pagevec pvec;



	if (length <= 0)

		return -ENOENT;



	pagevec_init(&pvec);



	do {

		unsigned nr_pages, i;



		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,

						end - 1);

		if (nr_pages == 0)

			break;



		for (i = 0; i < nr_pages; i++) {

			struct page *page = pvec.pages[i];



			if (page_seek_hole_data(inode, page, &lastoff, whence))

				goto check_range;

			lastoff = page_offset(page) + PAGE_SIZE;

		}

		pagevec_release(&pvec);

	} while (index < end);



	/* When no page at lastoff and we are not done, we found a hole. */

	if (whence != SEEK_HOLE)

		goto not_found;



check_range:

	if (lastoff < offset + length)

		goto out;

not_found:

	lastoff = -ENOENT;

out:

	pagevec_release(&pvec);

	return lastoff;

}





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 before or beyond the end of the file. */

	if (offset < 0 || 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 before or beyond the end of the file. */

	if (offset < 0 || 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:

fs/iomap/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
obj-$(CONFIG_FS_IOMAP)		+= iomap.o



iomap-y				+= \

					fiemap.o

					fiemap.o \

					seek.o



iomap-$(CONFIG_SWAP)		+= swapfile.o

fs/iomap/seek.c

0 → 100644
+214 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (C) 2017 Red Hat, Inc.

 * Copyright (c) 2018 Christoph Hellwig.

 */

#include <linux/module.h>

#include <linux/compiler.h>

#include <linux/fs.h>

#include <linux/iomap.h>

#include <linux/pagemap.h>

#include <linux/pagevec.h>



#include "../internal.h"



/*

 * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.

 * Returns true if found and updates @lastoff to the offset in file.

 */

static bool

page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,

		int whence)

{

	const struct address_space_operations *ops = inode->i_mapping->a_ops;

	unsigned int bsize = i_blocksize(inode), off;

	bool seek_data = whence == SEEK_DATA;

	loff_t poff = page_offset(page);



	if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE))

		return false;



	if (*lastoff < poff) {

		/*

		 * Last offset smaller than the start of the page means we found

		 * a hole:

		 */

		if (whence == SEEK_HOLE)

			return true;

		*lastoff = poff;

	}



	/*

	 * Just check the page unless we can and should check block ranges:

	 */

	if (bsize == PAGE_SIZE || !ops->is_partially_uptodate)

		return PageUptodate(page) == seek_data;



	lock_page(page);

	if (unlikely(page->mapping != inode->i_mapping))

		goto out_unlock_not_found;



	for (off = 0; off < PAGE_SIZE; off += bsize) {

		if (offset_in_page(*lastoff) >= off + bsize)

			continue;

		if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {

			unlock_page(page);

			return true;

		}

		*lastoff = poff + off + bsize;

	}



out_unlock_not_found:

	unlock_page(page);

	return false;

}



/*

 * Seek for SEEK_DATA / SEEK_HOLE in the page cache.

 *

 * Within unwritten extents, the page cache determines which parts are holes

 * and which are data: uptodate buffer heads count as data; everything else

 * counts as a hole.

 *

 * Returns the resulting offset on successs, and -ENOENT otherwise.

 */

static loff_t

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

		int whence)

{

	pgoff_t index = offset >> PAGE_SHIFT;

	pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);

	loff_t lastoff = offset;

	struct pagevec pvec;



	if (length <= 0)

		return -ENOENT;



	pagevec_init(&pvec);



	do {

		unsigned nr_pages, i;



		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,

						end - 1);

		if (nr_pages == 0)

			break;



		for (i = 0; i < nr_pages; i++) {

			struct page *page = pvec.pages[i];



			if (page_seek_hole_data(inode, page, &lastoff, whence))

				goto check_range;

			lastoff = page_offset(page) + PAGE_SIZE;

		}

		pagevec_release(&pvec);

	} while (index < end);



	/* When no page at lastoff and we are not done, we found a hole. */

	if (whence != SEEK_HOLE)

		goto not_found;



check_range:

	if (lastoff < offset + length)

		goto out;

not_found:

	lastoff = -ENOENT;

out:

	pagevec_release(&pvec);

	return lastoff;

}





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 before or beyond the end of the file. */

	if (offset < 0 || 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 before or beyond the end of the file. */

	if (offset < 0 || 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);