Commit 9b8b7d35 authored by Amir Goldstein's avatar Amir Goldstein Committed by Theodore Ts'o
Browse files

ext4: teach ext4_mb_init_cache() to skip uptodate buddy caches 



After online resize which adds new groups, some of the groups
in a buddy page may be initialized and uptodate, while other
(new ones) may be uninitialized.

The indication for init of new block groups is when ext4_mb_init_cache()
is called with an uptodate buddy page. In this case, initialized groups
on that buddy page must be skipped when initializing the buddy cache.

Signed-off-by: default avatarAmir Goldstein <amir73il@users.sf.net>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 2de8807b

fs/ext4/mballoc.c

+25 −8
Original line number Diff line number Diff line
@@ -787,6 +787,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore) 
	struct inode *inode;

	char *data;

	char *bitmap;

	struct ext4_group_info *grinfo;



	mb_debug(1, "init page %lu\n", page->index);
@@ -819,6 +820,18 @@ static int ext4_mb_init_cache(struct page *page, char *incore) 
		if (first_group + i >= ngroups)

			break;



		grinfo = ext4_get_group_info(sb, first_group + i);

		/*

		 * If page is uptodate then we came here after online resize

		 * which added some new uninitialized group info structs, so

		 * we must skip all initialized uptodate buddies on the page,

		 * which may be currently in use by an allocating task.

		 */

		if (PageUptodate(page) && !EXT4_MB_GRP_NEED_INIT(grinfo)) {

			bh[i] = NULL;

			continue;

		}



		err = -EIO;

		desc = ext4_get_group_desc(sb, first_group + i, NULL);

		if (desc == NULL)
@@ -871,26 +884,28 @@ static int ext4_mb_init_cache(struct page *page, char *incore) 
	}



	/* wait for I/O completion */

	for (i = 0; i < groups_per_page && bh[i]; i++)

	for (i = 0; i < groups_per_page; i++)

		if (bh[i])

			wait_on_buffer(bh[i]);



	err = -EIO;

	for (i = 0; i < groups_per_page && bh[i]; i++)

		if (!buffer_uptodate(bh[i]))

	for (i = 0; i < groups_per_page; i++)

		if (bh[i] && !buffer_uptodate(bh[i]))

			goto out;



	err = 0;

	first_block = page->index * blocks_per_page;

	/* init the page  */

	memset(page_address(page), 0xff, PAGE_CACHE_SIZE);

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

		int group;

		struct ext4_group_info *grinfo;



		group = (first_block + i) >> 1;

		if (group >= ngroups)

			break;



		if (!bh[group - first_group])

			/* skip initialized uptodate buddy */

			continue;



		/*

		 * data carry information regarding this

		 * particular group in the format specified
@@ -919,6 +934,8 @@ static int ext4_mb_init_cache(struct page *page, char *incore) 
			 * incore got set to the group block bitmap below

			 */

			ext4_lock_group(sb, group);

			/* init the buddy */

			memset(data, 0xff, blocksize);

			ext4_mb_generate_buddy(sb, data, incore, group);

			ext4_unlock_group(sb, group);

			incore = NULL;
@@ -948,7 +965,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore) 


out:

	if (bh) {

		for (i = 0; i < groups_per_page && bh[i]; i++)

		for (i = 0; i < groups_per_page; i++)

			brelse(bh[i]);

		if (bh != &bhs)

			kfree(bh);

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