ext4: Add delayed allocation support in data=writeback mode (64769240) · Commits · 戴 / test

fs/ext4/ext4.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -536,6 +536,7 @@ do { \
		#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
		#define EXT4_MOUNT_I_VERSION 0x2000000 /* i_version support */
		#define EXT4_MOUNT_MBALLOC 0x4000000 /* Buddy allocation support */
		#define EXT4_MOUNT_DELALLOC 0x8000000 /* Delalloc support */
		/* Compatibility, for having both ext2_fs.h and ext4_fs.h included at once */
		#ifndef _LINUX_EXT2_FS_H
		#define clear_opt(o, opt) o &= ~EXT4_MOUNT_##opt

fs/ext4/inode.c

+694 −5

Original line number	Diff line number	Diff line
		@@ -32,6 +32,7 @@
		#include <linux/string.h>
		#include <linux/buffer_head.h>
		#include <linux/writeback.h>
		#include <linux/pagevec.h>
		#include <linux/mpage.h>
		#include <linux/uio.h>
		#include <linux/bio.h>
		@@ -46,6 +47,8 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
		new_size);
		}

		static void ext4_invalidatepage(struct page *page, unsigned long offset);

		/*
		* Test whether an inode is a fast symlink.
		*/
		@@ -1407,6 +1410,669 @@ static int ext4_journalled_write_end(struct file *file,
		return ret ? ret : copied;
		}

		/*
		* Delayed allocation stuff
		*/

		struct mpage_da_data {
		struct inode *inode;
		struct buffer_head lbh; /* extent of blocks */
		unsigned long first_page, next_page; /* extent of pages */
		get_block_t *get_block;
		struct writeback_control *wbc;
		};

		/*
		* mpage_da_submit_io - walks through extent of pages and try to write
		* them with __mpage_writepage()
		*
		* @mpd->inode: inode
		* @mpd->first_page: first page of the extent
		* @mpd->next_page: page after the last page of the extent
		* @mpd->get_block: the filesystem's block mapper function
		*
		* By the time mpage_da_submit_io() is called we expect all blocks
		* to be allocated. this may be wrong if allocation failed.
		*
		* As pages are already locked by write_cache_pages(), we can't use it
		*/
		static int mpage_da_submit_io(struct mpage_da_data *mpd)
		{
		struct address_space *mapping = mpd->inode->i_mapping;
		struct mpage_data mpd_pp = {
		.bio = NULL,
		.last_block_in_bio = 0,
		.get_block = mpd->get_block,
		.use_writepage = 1,
		};
		int ret = 0, err, nr_pages, i;
		unsigned long index, end;
		struct pagevec pvec;

		BUG_ON(mpd->next_page <= mpd->first_page);

		pagevec_init(&pvec, 0);
		index = mpd->first_page;
		end = mpd->next_page - 1;

		while (index <= end) {
		/* XXX: optimize tail */
		nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
		if (nr_pages == 0)
		break;
		for (i = 0; i < nr_pages; i++) {
		struct page *page = pvec.pages[i];

		index = page->index;
		if (index > end)
		break;
		index++;

		err = __mpage_writepage(page, mpd->wbc, &mpd_pp);

		/*
		* In error case, we have to continue because
		* remaining pages are still locked
		* XXX: unlock and re-dirty them?
		*/
		if (ret == 0)
		ret = err;
		}
		pagevec_release(&pvec);
		}
		if (mpd_pp.bio)
		mpage_bio_submit(WRITE, mpd_pp.bio);

		return ret;
		}

		/*
		* mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
		*
		* @mpd->inode - inode to walk through
		* @exbh->b_blocknr - first block on a disk
		* @exbh->b_size - amount of space in bytes
		* @logical - first logical block to start assignment with
		*
		* the function goes through all passed space and put actual disk
		* block numbers into buffer heads, dropping BH_Delay
		*/
		static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
		struct buffer_head *exbh)
		{
		struct inode *inode = mpd->inode;
		struct address_space *mapping = inode->i_mapping;
		int blocks = exbh->b_size >> inode->i_blkbits;
		sector_t pblock = exbh->b_blocknr, cur_logical;
		struct buffer_head head, bh;
		unsigned long index, end;
		struct pagevec pvec;
		int nr_pages, i;

		index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
		end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
		cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);

		pagevec_init(&pvec, 0);

		while (index <= end) {
		/* XXX: optimize tail */
		nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
		if (nr_pages == 0)
		break;
		for (i = 0; i < nr_pages; i++) {
		struct page *page = pvec.pages[i];

		index = page->index;
		if (index > end)
		break;
		index++;

		BUG_ON(!PageLocked(page));
		BUG_ON(PageWriteback(page));
		BUG_ON(!page_has_buffers(page));

		bh = page_buffers(page);
		head = bh;

		/* skip blocks out of the range */
		do {
		if (cur_logical >= logical)
		break;
		cur_logical++;
		} while ((bh = bh->b_this_page) != head);

		do {
		if (cur_logical >= logical + blocks)
		break;

		if (buffer_delay(bh)) {
		bh->b_blocknr = pblock;
		clear_buffer_delay(bh);
		} else if (buffer_mapped(bh)) {
		BUG_ON(bh->b_blocknr != pblock);
		}

		cur_logical++;
		pblock++;
		} while ((bh = bh->b_this_page) != head);
		}
		pagevec_release(&pvec);
		}
		}


		/*
		* __unmap_underlying_blocks - just a helper function to unmap
		* set of blocks described by @bh
		*/
		static inline void __unmap_underlying_blocks(struct inode *inode,
		struct buffer_head *bh)
		{
		struct block_device *bdev = inode->i_sb->s_bdev;
		int blocks, i;

		blocks = bh->b_size >> inode->i_blkbits;
		for (i = 0; i < blocks; i++)
		unmap_underlying_metadata(bdev, bh->b_blocknr + i);
		}

		/*
		* mpage_da_map_blocks - go through given space
		*
		* @mpd->lbh - bh describing space
		* @mpd->get_block - the filesystem's block mapper function
		*
		* The function skips space we know is already mapped to disk blocks.
		*
		* The function ignores errors ->get_block() returns, thus real
		* error handling is postponed to __mpage_writepage()
		*/
		static void mpage_da_map_blocks(struct mpage_da_data *mpd)
		{
		struct buffer_head *lbh = &mpd->lbh;
		int err = 0, remain = lbh->b_size;
		sector_t next = lbh->b_blocknr;
		struct buffer_head new;

		/*
		* We consider only non-mapped and non-allocated blocks
		*/
		if (buffer_mapped(lbh) && !buffer_delay(lbh))
		return;

		while (remain) {
		new.b_state = lbh->b_state;
		new.b_blocknr = 0;
		new.b_size = remain;
		err = mpd->get_block(mpd->inode, next, &new, 1);
		if (err) {
		/*
		* Rather than implement own error handling
		* here, we just leave remaining blocks
		* unallocated and try again with ->writepage()
		*/
		break;
		}
		BUG_ON(new.b_size == 0);

		if (buffer_new(&new))
		__unmap_underlying_blocks(mpd->inode, &new);

		/*
		* If blocks are delayed marked, we need to
		* put actual blocknr and drop delayed bit
		*/
		if (buffer_delay(lbh))
		mpage_put_bnr_to_bhs(mpd, next, &new);

		/* go for the remaining blocks */
		next += new.b_size >> mpd->inode->i_blkbits;
		remain -= new.b_size;
		}
		}

		#define BH_FLAGS ((1 << BH_Uptodate) \| (1 << BH_Mapped) \| (1 << BH_Delay))

		/*
		* mpage_add_bh_to_extent - try to add one more block to extent of blocks
		*
		* @mpd->lbh - extent of blocks
		* @logical - logical number of the block in the file
		* @bh - bh of the block (used to access block's state)
		*
		* the function is used to collect contig. blocks in same state
		*/
		static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
		sector_t logical, struct buffer_head *bh)
		{
		struct buffer_head *lbh = &mpd->lbh;
		sector_t next;

		next = lbh->b_blocknr + (lbh->b_size >> mpd->inode->i_blkbits);

		/*
		* First block in the extent
		*/
		if (lbh->b_size == 0) {
		lbh->b_blocknr = logical;
		lbh->b_size = bh->b_size;
		lbh->b_state = bh->b_state & BH_FLAGS;
		return;
		}

		/*
		* Can we merge the block to our big extent?
		*/
		if (logical == next && (bh->b_state & BH_FLAGS) == lbh->b_state) {
		lbh->b_size += bh->b_size;
		return;
		}

		/*
		* We couldn't merge the block to our extent, so we
		* need to flush current extent and start new one
		*/
		mpage_da_map_blocks(mpd);

		/*
		* Now start a new extent
		*/
		lbh->b_size = bh->b_size;
		lbh->b_state = bh->b_state & BH_FLAGS;
		lbh->b_blocknr = logical;
		}

		/*
		* __mpage_da_writepage - finds extent of pages and blocks
		*
		* @page: page to consider
		* @wbc: not used, we just follow rules
		* @data: context
		*
		* The function finds extents of pages and scan them for all blocks.
		*/
		static int __mpage_da_writepage(struct page *page,
		struct writeback_control wbc, void data)
		{
		struct mpage_da_data *mpd = data;
		struct inode *inode = mpd->inode;
		struct buffer_head bh, head, fake;
		sector_t logical;

		/*
		* Can we merge this page to current extent?
		*/
		if (mpd->next_page != page->index) {
		/*
		* Nope, we can't. So, we map non-allocated blocks
		* and start IO on them using __mpage_writepage()
		*/
		if (mpd->next_page != mpd->first_page) {
		mpage_da_map_blocks(mpd);
		mpage_da_submit_io(mpd);
		}

		/*
		* Start next extent of pages ...
		*/
		mpd->first_page = page->index;

		/*
		* ... and blocks
		*/
		mpd->lbh.b_size = 0;
		mpd->lbh.b_state = 0;
		mpd->lbh.b_blocknr = 0;
		}

		mpd->next_page = page->index + 1;
		logical = (sector_t) page->index <<
		(PAGE_CACHE_SHIFT - inode->i_blkbits);

		if (!page_has_buffers(page)) {
		/*
		* There is no attached buffer heads yet (mmap?)
		* we treat the page asfull of dirty blocks
		*/
		bh = &fake;
		bh->b_size = PAGE_CACHE_SIZE;
		bh->b_state = 0;
		set_buffer_dirty(bh);
		set_buffer_uptodate(bh);
		mpage_add_bh_to_extent(mpd, logical, bh);
		} else {
		/*
		* Page with regular buffer heads, just add all dirty ones
		*/
		head = page_buffers(page);
		bh = head;
		do {
		BUG_ON(buffer_locked(bh));
		if (buffer_dirty(bh))
		mpage_add_bh_to_extent(mpd, logical, bh);
		logical++;
		} while ((bh = bh->b_this_page) != head);
		}

		return 0;
		}

		/*
		* mpage_da_writepages - walk the list of dirty pages of the given
		* address space, allocates non-allocated blocks, maps newly-allocated
		* blocks to existing bhs and issue IO them
		*
		* @mapping: address space structure to write
		* @wbc: subtract the number of written pages from *@wbc->nr_to_write
		* @get_block: the filesystem's block mapper function.
		*
		* This is a library function, which implements the writepages()
		* address_space_operation.
		*
		* In order to avoid duplication of logic that deals with partial pages,
		* multiple bio per page, etc, we find non-allocated blocks, allocate
		* them with minimal calls to ->get_block() and re-use __mpage_writepage()
		*
		* It's important that we call __mpage_writepage() only once for each
		* involved page, otherwise we'd have to implement more complicated logic
		* to deal with pages w/o PG_lock or w/ PG_writeback and so on.
		*
		* See comments to mpage_writepages()
		*/
		static int mpage_da_writepages(struct address_space *mapping,
		struct writeback_control *wbc,
		get_block_t get_block)
		{
		struct mpage_da_data mpd;
		int ret;

		if (!get_block)
		return generic_writepages(mapping, wbc);

		mpd.wbc = wbc;
		mpd.inode = mapping->host;
		mpd.lbh.b_size = 0;
		mpd.lbh.b_state = 0;
		mpd.lbh.b_blocknr = 0;
		mpd.first_page = 0;
		mpd.next_page = 0;
		mpd.get_block = get_block;

		ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, &mpd);

		/*
		* Handle last extent of pages
		*/
		if (mpd.next_page != mpd.first_page) {
		mpage_da_map_blocks(&mpd);
		mpage_da_submit_io(&mpd);
		}

		return ret;
		}

		/*
		* this is a special callback for ->write_begin() only
		* it's intention is to return mapped block or reserve space
		*/
		static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
		struct buffer_head *bh_result, int create)
		{
		int ret = 0;

		BUG_ON(create == 0);
		BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);

		/*
		* first, we need to know whether the block is allocated already
		* preallocated blocks are unmapped but should treated
		* the same as allocated blocks.
		*/
		ret = ext4_get_blocks_wrap(NULL, inode, iblock, 1, bh_result, 0, 0);
		if (ret == 0) {
		/* the block isn't allocated yet, let's reserve space */
		/* XXX: call reservation here */
		/*
		* XXX: __block_prepare_write() unmaps passed block,
		* is it OK?
		*/
		map_bh(bh_result, inode->i_sb, 0);
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
		} else if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);
		ret = 0;
		}

		return ret;
		}

		static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
		struct buffer_head *bh_result, int create)
		{
		int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
		unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
		loff_t disksize = EXT4_I(inode)->i_disksize;
		handle_t *handle = NULL;

		if (create) {
		handle = ext4_journal_start(inode, needed_blocks);
		if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out;
		}
		}

		ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
		bh_result, create, 0);
		if (ret > 0) {
		bh_result->b_size = (ret << inode->i_blkbits);

		/*
		* Update on-disk size along with block allocation
		* we don't use 'extend_disksize' as size may change
		* within already allocated block -bzzz
		*/
		disksize = ((loff_t) iblock + ret) << inode->i_blkbits;
		if (disksize > i_size_read(inode))
		disksize = i_size_read(inode);
		if (disksize > EXT4_I(inode)->i_disksize) {
		/*
		* XXX: replace with spinlock if seen contended -bzzz
		*/
		down_write(&EXT4_I(inode)->i_data_sem);
		if (disksize > EXT4_I(inode)->i_disksize)
		EXT4_I(inode)->i_disksize = disksize;
		up_write(&EXT4_I(inode)->i_data_sem);

		if (EXT4_I(inode)->i_disksize == disksize) {
		if (handle == NULL)
		handle = ext4_journal_start(inode, 1);
		if (!IS_ERR(handle))
		ext4_mark_inode_dirty(handle, inode);
		}
		}

		ret = 0;
		}

		out:
		if (handle && !IS_ERR(handle))
		ext4_journal_stop(handle);

		return ret;
		}
		/* FIXME!! only support data=writeback mode */
		static int ext4_da_writepage(struct page *page,
		struct writeback_control *wbc)
		{
		struct inode *inode = page->mapping->host;
		handle_t *handle = NULL;
		int ret = 0;
		int err;

		if (ext4_journal_current_handle())
		goto out_fail;

		handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
		if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out_fail;
		}

		if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
		ret = nobh_writepage(page, ext4_get_block, wbc);
		else
		ret = block_write_full_page(page, ext4_get_block, wbc);

		if (!ret && inode->i_size > EXT4_I(inode)->i_disksize) {
		EXT4_I(inode)->i_disksize = inode->i_size;
		ext4_mark_inode_dirty(handle, inode);
		}

		err = ext4_journal_stop(handle);
		if (!ret)
		ret = err;
		return ret;

		out_fail:
		redirty_page_for_writepage(wbc, page);
		unlock_page(page);
		return ret;
		}

		static int ext4_da_writepages(struct address_space *mapping,
		struct writeback_control *wbc)
		{
		return mpage_da_writepages(mapping, wbc, ext4_da_get_block_write);
		}

		static int ext4_da_write_begin(struct file file, struct address_space mapping,
		loff_t pos, unsigned len, unsigned flags,
		struct page pagep, void fsdata)
		{
		int ret;
		struct page *page;
		pgoff_t index;
		unsigned from, to;
		struct inode *inode = mapping->host;
		handle_t *handle;

		index = pos >> PAGE_CACHE_SHIFT;
		from = pos & (PAGE_CACHE_SIZE - 1);
		to = from + len;

		/*
		* With delayed allocation, we don't log the i_disksize update
		* if there is delayed block allocation. But we still need
		* to journalling the i_disksize update if writes to the end
		* of file which has an already mapped buffer.
		*/
		handle = ext4_journal_start(inode, 1);
		if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		goto out;
		}

		page = __grab_cache_page(mapping, index);
		if (!page)
		return -ENOMEM;
		*pagep = page;

		ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
		ext4_da_get_block_prep);
		if (ret < 0) {
		unlock_page(page);
		ext4_journal_stop(handle);
		page_cache_release(page);
		}

		out:
		return ret;
		}

		static int ext4_bh_unmapped_or_delay(handle_t handle, struct buffer_head bh)
		{
		return !buffer_mapped(bh) \|\| buffer_delay(bh);
		}

		static int ext4_da_write_end(struct file *file,
		struct address_space *mapping,
		loff_t pos, unsigned len, unsigned copied,
		struct page page, void fsdata)
		{
		struct inode *inode = mapping->host;
		int ret = 0, ret2;
		handle_t *handle = ext4_journal_current_handle();
		loff_t new_i_size;

		/*
		* generic_write_end() will run mark_inode_dirty() if i_size
		* changes. So let's piggyback the i_disksize mark_inode_dirty
		* into that.
		*/

		new_i_size = pos + copied;
		if (new_i_size > EXT4_I(inode)->i_disksize)
		if (!walk_page_buffers(NULL, page_buffers(page),
		0, len, NULL, ext4_bh_unmapped_or_delay)){
		/*
		* Updating i_disksize when extending file without
		* needing block allocation
		*/
		if (ext4_should_order_data(inode))
		ret = ext4_jbd2_file_inode(handle, inode);

		EXT4_I(inode)->i_disksize = new_i_size;
		}
		ret2 = generic_write_end(file, mapping, pos, len, copied,
		page, fsdata);
		copied = ret2;
		if (ret2 < 0)
		ret = ret2;
		ret2 = ext4_journal_stop(handle);
		if (!ret)
		ret = ret2;

		return ret ? ret : copied;
		}

		static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
		{
		struct buffer_head head, bh;
		unsigned int curr_off = 0;

		/*
		* Drop reserved blocks
		*/
		BUG_ON(!PageLocked(page));
		if (!page_has_buffers(page))
		goto out;

		head = page_buffers(page);
		bh = head;
		do {
		unsigned int next_off = curr_off + bh->b_size;

		/*
		* is this block fully invalidated?
		*/
		if (offset <= curr_off && buffer_delay(bh)) {
		clear_buffer_delay(bh);
		/* XXX: add real stuff here */
		}
		curr_off = next_off;
		bh = bh->b_this_page;
		} while (bh != head);

		out:
		ext4_invalidatepage(page, offset);

		return;
		}


		/*
		* bmap() is special. It gets used by applications such as lilo and by
		* the swapper to find the on-disk block of a specific piece of data.
		@@ -1427,6 +2093,16 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
		journal_t *journal;
		int err;

		if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
		test_opt(inode->i_sb, DELALLOC)) {
		/*
		* With delalloc we want to sync the file
		* so that we can make sure we allocate
		* blocks for file
		*/
		filemap_write_and_wait(mapping);
		}

		if (EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
		/*
		* This is a REALLY heavyweight approach, but the use of
		@@ -1471,11 +2147,6 @@ static int bput_one(handle_t handle, struct buffer_head bh)
		return 0;
		}

		static int ext4_bh_unmapped_or_delay(handle_t handle, struct buffer_head bh)
		{
		return !buffer_mapped(bh) \|\| buffer_delay(bh);
		}

		/*
		* Note that we don't need to start a transaction unless we're journaling data
		* because we should have holes filled from ext4_page_mkwrite(). We even don't
		@@ -1832,10 +2503,28 @@ static const struct address_space_operations ext4_journalled_aops = {
		.releasepage = ext4_releasepage,
		};

		static const struct address_space_operations ext4_da_aops = {
		.readpage = ext4_readpage,
		.readpages = ext4_readpages,
		.writepage = ext4_da_writepage,
		.writepages = ext4_da_writepages,
		.sync_page = block_sync_page,
		.write_begin = ext4_da_write_begin,
		.write_end = ext4_da_write_end,
		.bmap = ext4_bmap,
		.invalidatepage = ext4_da_invalidatepage,
		.releasepage = ext4_releasepage,
		.direct_IO = ext4_direct_IO,
		.migratepage = buffer_migrate_page,
		};

		void ext4_set_aops(struct inode *inode)
		{
		if (ext4_should_order_data(inode))
		inode->i_mapping->a_ops = &ext4_ordered_aops;
		else if (ext4_should_writeback_data(inode) &&
		test_opt(inode->i_sb, DELALLOC))
		inode->i_mapping->a_ops = &ext4_da_aops;
		else if (ext4_should_writeback_data(inode))
		inode->i_mapping->a_ops = &ext4_writeback_aops;
		else

fs/ext4/super.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -898,7 +898,7 @@ enum {
		Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
		Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
		Opt_grpquota, Opt_extents, Opt_noextents, Opt_i_version,
		Opt_mballoc, Opt_nomballoc, Opt_stripe,
		Opt_mballoc, Opt_nomballoc, Opt_stripe, Opt_delalloc,
		};

		static match_table_t tokens = {
		@@ -957,6 +957,7 @@ static match_table_t tokens = {
		{Opt_nomballoc, "nomballoc"},
		{Opt_stripe, "stripe=%u"},
		{Opt_resize, "resize"},
		{Opt_delalloc, "delalloc"},
		{Opt_err, NULL},
		};

		@@ -1335,6 +1336,9 @@ set_qf_format:
		return 0;
		sbi->s_stripe = option;
		break;
		case Opt_delalloc:
		set_opt(sbi->s_mount_opt, DELALLOC);
		break;
		default:
		printk (KERN_ERR
		"EXT4-fs: Unrecognized mount option \"%s\" "

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