ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA (545052e9) · Commits · 戴 / test

fs/ext4/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,7 @@ config EXT4_FS
		select CRC16
		select CRYPTO
		select CRYPTO_CRC32C
		select FS_IOMAP
		help
		This is the next generation of the ext3 filesystem.

fs/ext4/ext4.h

+0 −3

Original line number	Diff line number	Diff line
		@@ -2515,9 +2515,6 @@ extern void ext4_da_update_reserve_space(struct inode *inode,
		int used, int quota_claim);
		extern int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk,
		ext4_fsblk_t pblk, ext4_lblk_t len);
		extern int ext4_get_next_extent(struct inode *inode, ext4_lblk_t lblk,
		unsigned int map_len,
		struct extent_status *result);

		/* indirect.c */
		extern int ext4_ind_map_blocks(handle_t handle, struct inode inode,

fs/ext4/file.c

+14 −249

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@

		#include <linux/time.h>
		#include <linux/fs.h>
		#include <linux/iomap.h>
		#include <linux/mount.h>
		#include <linux/path.h>
		#include <linux/dax.h>
		@@ -437,248 +438,6 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
		return dquot_file_open(inode, filp);
		}

		/*
		* Here we use ext4_map_blocks() to get a block mapping for a extent-based
		* file rather than ext4_ext_walk_space() because we can introduce
		* SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
		* function. When extent status tree has been fully implemented, it will
		* track all extent status for a file and we can directly use it to
		* retrieve the offset for SEEK_DATA/SEEK_HOLE.
		*/

		/*
		* When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
		* lookup page cache to check whether or not there has some data between
		* [startoff, endoff] because, if this range contains an unwritten extent,
		* we determine this extent as a data or a hole according to whether the
		* page cache has data or not.
		*/
		static int ext4_find_unwritten_pgoff(struct inode *inode,
		int whence,
		ext4_lblk_t end_blk,
		loff_t *offset)
		{
		struct pagevec pvec;
		unsigned int blkbits;
		pgoff_t index;
		pgoff_t end;
		loff_t endoff;
		loff_t startoff;
		loff_t lastoff;
		int found = 0;

		blkbits = inode->i_sb->s_blocksize_bits;
		startoff = *offset;
		lastoff = startoff;
		endoff = (loff_t)end_blk << blkbits;

		index = startoff >> PAGE_SHIFT;
		end = (endoff - 1) >> PAGE_SHIFT;

		pagevec_init(&pvec, 0);
		do {
		int i;
		unsigned long nr_pages;

		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
		&index, end);
		if (nr_pages == 0)
		break;

		for (i = 0; i < nr_pages; i++) {
		struct page *page = pvec.pages[i];
		struct buffer_head bh, head;

		/*
		* If current offset is smaller than the page offset,
		* there is a hole at this offset.
		*/
		if (whence == SEEK_HOLE && lastoff < endoff &&
		lastoff < page_offset(pvec.pages[i])) {
		found = 1;
		*offset = lastoff;
		goto out;
		}

		lock_page(page);

		if (unlikely(page->mapping != inode->i_mapping)) {
		unlock_page(page);
		continue;
		}

		if (!page_has_buffers(page)) {
		unlock_page(page);
		continue;
		}

		if (page_has_buffers(page)) {
		lastoff = page_offset(page);
		bh = head = page_buffers(page);
		do {
		if (lastoff + bh->b_size <= startoff)
		goto next;
		if (buffer_uptodate(bh) \|\|
		buffer_unwritten(bh)) {
		if (whence == SEEK_DATA)
		found = 1;
		} else {
		if (whence == SEEK_HOLE)
		found = 1;
		}
		if (found) {
		*offset = max_t(loff_t,
		startoff, lastoff);
		unlock_page(page);
		goto out;
		}
		next:
		lastoff += bh->b_size;
		bh = bh->b_this_page;
		} while (bh != head);
		}

		lastoff = page_offset(page) + PAGE_SIZE;
		unlock_page(page);
		}

		pagevec_release(&pvec);
		} while (index <= end);

		/* There are no pages upto endoff - that would be a hole in there. */
		if (whence == SEEK_HOLE && lastoff < endoff) {
		found = 1;
		*offset = lastoff;
		}
		out:
		pagevec_release(&pvec);
		return found;
		}

		/*
		* ext4_seek_data() retrieves the offset for SEEK_DATA.
		*/
		static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
		{
		struct inode *inode = file->f_mapping->host;
		struct extent_status es;
		ext4_lblk_t start, last, end;
		loff_t dataoff, isize;
		int blkbits;
		int ret;

		inode_lock(inode);

		isize = i_size_read(inode);
		if (offset < 0 \|\| offset >= isize) {
		inode_unlock(inode);
		return -ENXIO;
		}

		blkbits = inode->i_sb->s_blocksize_bits;
		start = offset >> blkbits;
		last = start;
		end = isize >> blkbits;
		dataoff = offset;

		do {
		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
		if (ret <= 0) {
		/* No extent found -> no data */
		if (ret == 0)
		ret = -ENXIO;
		inode_unlock(inode);
		return ret;
		}

		last = es.es_lblk;
		if (last != start)
		dataoff = (loff_t)last << blkbits;
		if (!ext4_es_is_unwritten(&es))
		break;

		/*
		* If there is a unwritten extent at this offset,
		* it will be as a data or a hole according to page
		* cache that has data or not.
		*/
		if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
		es.es_lblk + es.es_len, &dataoff))
		break;
		last += es.es_len;
		dataoff = (loff_t)last << blkbits;
		cond_resched();
		} while (last <= end);

		inode_unlock(inode);

		if (dataoff > isize)
		return -ENXIO;

		return vfs_setpos(file, dataoff, maxsize);
		}

		/*
		* ext4_seek_hole() retrieves the offset for SEEK_HOLE.
		*/
		static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
		{
		struct inode *inode = file->f_mapping->host;
		struct extent_status es;
		ext4_lblk_t start, last, end;
		loff_t holeoff, isize;
		int blkbits;
		int ret;

		inode_lock(inode);

		isize = i_size_read(inode);
		if (offset < 0 \|\| offset >= isize) {
		inode_unlock(inode);
		return -ENXIO;
		}

		blkbits = inode->i_sb->s_blocksize_bits;
		start = offset >> blkbits;
		last = start;
		end = isize >> blkbits;
		holeoff = offset;

		do {
		ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
		if (ret < 0) {
		inode_unlock(inode);
		return ret;
		}
		/* Found a hole? */
		if (ret == 0 \|\| es.es_lblk > last) {
		if (last != start)
		holeoff = (loff_t)last << blkbits;
		break;
		}
		/*
		* If there is a unwritten extent at this offset,
		* it will be as a data or a hole according to page
		* cache that has data or not.
		*/
		if (ext4_es_is_unwritten(&es) &&
		ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
		last + es.es_len, &holeoff))
		break;

		last += es.es_len;
		holeoff = (loff_t)last << blkbits;
		cond_resched();
		} while (last <= end);

		inode_unlock(inode);

		if (holeoff > isize)
		holeoff = isize;

		return vfs_setpos(file, holeoff, maxsize);
		}

		/*
		* ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
		* by calling generic_file_llseek_size() with the appropriate maxbytes
		@@ -695,18 +454,24 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
		maxbytes = inode->i_sb->s_maxbytes;

		switch (whence) {
		case SEEK_SET:
		case SEEK_CUR:
		case SEEK_END:
		default:
		return generic_file_llseek_size(file, offset, whence,
		maxbytes, i_size_read(inode));
		case SEEK_DATA:
		return ext4_seek_data(file, offset, maxbytes);
		case SEEK_HOLE:
		return ext4_seek_hole(file, offset, maxbytes);
		inode_lock_shared(inode);
		offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops);
		inode_unlock_shared(inode);
		break;
		case SEEK_DATA:
		inode_lock_shared(inode);
		offset = iomap_seek_data(inode, offset, &ext4_iomap_ops);
		inode_unlock_shared(inode);
		break;
		}

		return -EINVAL;
		if (offset < 0)
		return offset;
		return vfs_setpos(file, offset, maxbytes);
		}

		const struct file_operations ext4_file_operations = {

fs/ext4/inode.c

+34 −75

Original line number	Diff line number	Diff line
		@@ -3393,7 +3393,6 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
		return try_to_free_buffers(page);
		}

		#ifdef CONFIG_FS_DAX
		static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
		unsigned flags, struct iomap *iomap)
		{
		@@ -3402,6 +3401,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
		unsigned long first_block = offset >> blkbits;
		unsigned long last_block = (offset + length - 1) >> blkbits;
		struct ext4_map_blocks map;
		bool delalloc = false;
		int ret;


		@@ -3422,9 +3422,33 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
		map.m_lblk = first_block;
		map.m_len = last_block - first_block + 1;

		if (!(flags & IOMAP_WRITE)) {
		if (flags & IOMAP_REPORT) {
		ret = ext4_map_blocks(NULL, inode, &map, 0);
		if (ret < 0)
		return ret;

		if (ret == 0) {
		ext4_lblk_t end = map.m_lblk + map.m_len - 1;
		struct extent_status es;

		ext4_es_find_delayed_extent_range(inode, map.m_lblk, end, &es);

		if (!es.es_len \|\| es.es_lblk > end) {
		/* entire range is a hole */
		} else if (es.es_lblk > map.m_lblk) {
		/* range starts with a hole */
		map.m_len = es.es_lblk - map.m_lblk;
		} else {
		ext4_lblk_t offs = 0;

		if (es.es_lblk < map.m_lblk)
		offs = map.m_lblk - es.es_lblk;
		map.m_lblk = es.es_lblk + offs;
		map.m_len = es.es_len - offs;
		delalloc = true;
		}
		}
		} else if (flags & IOMAP_WRITE) {
		int dio_credits;
		handle_t *handle;
		int retries = 0;
		@@ -3475,17 +3499,21 @@ retry:
		}
		}
		ext4_journal_stop(handle);
		} else {
		ret = ext4_map_blocks(NULL, inode, &map, 0);
		if (ret < 0)
		return ret;
		}

		iomap->flags = 0;
		iomap->bdev = inode->i_sb->s_bdev;
		iomap->dax_dev = sbi->s_daxdev;
		iomap->offset = first_block << blkbits;
		iomap->length = (u64)map.m_len << blkbits;

		if (ret == 0) {
		iomap->type = IOMAP_HOLE;
		iomap->type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE;
		iomap->addr = IOMAP_NULL_ADDR;
		iomap->length = (u64)map.m_len << blkbits;
		} else {
		if (map.m_flags & EXT4_MAP_MAPPED) {
		iomap->type = IOMAP_MAPPED;
		@@ -3496,11 +3524,11 @@ retry:
		return -EIO;
		}
		iomap->addr = (u64)map.m_pblk << blkbits;
		iomap->length = (u64)map.m_len << blkbits;
		}

		if (map.m_flags & EXT4_MAP_NEW)
		iomap->flags \|= IOMAP_F_NEW;

		return 0;
		}

		@@ -3561,8 +3589,6 @@ const struct iomap_ops ext4_iomap_ops = {
		.iomap_end = ext4_iomap_end,
		};

		#endif

		static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
		ssize_t size, void *private)
		{
		@@ -6118,70 +6144,3 @@ int ext4_filemap_fault(struct vm_fault *vmf)

		return err;
		}

		/*
		* Find the first extent at or after @lblk in an inode that is not a hole.
		* Search for @map_len blocks at most. The extent is returned in @result.
		*
		* The function returns 1 if we found an extent. The function returns 0 in
		* case there is no extent at or after @lblk and in that case also sets
		* @result->es_len to 0. In case of error, the error code is returned.
		*/
		int ext4_get_next_extent(struct inode *inode, ext4_lblk_t lblk,
		unsigned int map_len, struct extent_status *result)
		{
		struct ext4_map_blocks map;
		struct extent_status es = {};
		int ret;

		map.m_lblk = lblk;
		map.m_len = map_len;

		/*
		* For non-extent based files this loop may iterate several times since
		* we do not determine full hole size.
		*/
		while (map.m_len > 0) {
		ret = ext4_map_blocks(NULL, inode, &map, 0);
		if (ret < 0)
		return ret;
		/* There's extent covering m_lblk? Just return it. */
		if (ret > 0) {
		int status;

		ext4_es_store_pblock(result, map.m_pblk);
		result->es_lblk = map.m_lblk;
		result->es_len = map.m_len;
		if (map.m_flags & EXT4_MAP_UNWRITTEN)
		status = EXTENT_STATUS_UNWRITTEN;
		else
		status = EXTENT_STATUS_WRITTEN;
		ext4_es_store_status(result, status);
		return 1;
		}
		ext4_es_find_delayed_extent_range(inode, map.m_lblk,
		map.m_lblk + map.m_len - 1,
		&es);
		/* Is delalloc data before next block in extent tree? */
		if (es.es_len && es.es_lblk < map.m_lblk + map.m_len) {
		ext4_lblk_t offset = 0;

		if (es.es_lblk < lblk)
		offset = lblk - es.es_lblk;
		result->es_lblk = es.es_lblk + offset;
		ext4_es_store_pblock(result,
		ext4_es_pblock(&es) + offset);
		result->es_len = es.es_len - offset;
		ext4_es_store_status(result, ext4_es_status(&es));

		return 1;
		}
		/* There's a hole at m_lblk, advance us after it */
		map.m_lblk += map.m_len;
		map_len -= map.m_len;
		map.m_len = map_len;
		cond_resched();
		}
		result->es_len = 0;
		return 0;
		}

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