ext4: Use EXT4_GROUP_INFO_NEED_INIT_BIT during resize

The new groups added during resize are flagged as
need_init group. Make sure we properly initialize these
groups. When we have block size < page size and we are adding
new groups the page may still be marked uptodate even though
we haven't initialized the group. While forcing the init
of buddy cache we need to make sure other groups part of the
same page of buddy cache is not using the cache.
group_info->alloc_sem is added to ensure the same.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
cc: stable@kernel.org

fs/ext4/balloc.c

@@ -381,6 +381,7 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 
 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
+	grp = ext4_get_group_info(sb, block_group);
 	/*
 	 * Check to see if we are freeing blocks across a group
 	 * boundary.
@@ -425,7 +426,11 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	err = ext4_journal_get_write_access(handle, gd_bh);
 	if (err)
 		goto error_return;
-
+	/*
+	 * make sure we don't allow a parallel init on other groups in the
+	 * same buddy cache
+	 */
+	down_write(&grp->alloc_sem);
 	for (i = 0, blocks_freed = 0; i < count; i++) {
 		BUFFER_TRACE(bitmap_bh, "clear bit");
 		if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
@@ -450,6 +455,13 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 		sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
 		spin_unlock(sb_bgl_lock(sbi, flex_group));
 	}
+	/*
+	 * request to reload the buddy with the
+	 * new bitmap information
+	 */
+	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
+	ext4_mb_update_group_info(grp, blocks_freed);
+	up_write(&grp->alloc_sem);
 
 	/* We dirtied the bitmap block */
 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
@@ -461,13 +473,6 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 	if (!err)
 		err = ret;
 	sb->s_dirt = 1;
-	/*
-	 * request to reload the buddy with the
-	 * new bitmap information
-	 */
-	grp = ext4_get_group_info(sb, block_group);
-	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
-	ext4_mb_update_group_info(grp, blocks_freed);
 
 error_return:
 	brelse(bitmap_bh);

fs/ext4/ext4.h

@@ -1060,12 +1060,13 @@ extern int __init init_ext4_mballoc(void);
 extern void exit_ext4_mballoc(void);
 extern void ext4_mb_free_blocks(handle_t *, struct inode *,
 		unsigned long, unsigned long, int, unsigned long *);
-extern int ext4_mb_add_more_groupinfo(struct super_block *sb,
+extern int ext4_mb_add_groupinfo(struct super_block *sb,
 		ext4_group_t i, struct ext4_group_desc *desc);
 extern void ext4_mb_update_group_info(struct ext4_group_info *grp,
 		ext4_grpblk_t add);
-
-
+extern int ext4_mb_get_buddy_cache_lock(struct super_block *, ext4_group_t);
+extern void ext4_mb_put_buddy_cache_lock(struct super_block *,
+						ext4_group_t, int);
 /* inode.c */
 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
 		struct buffer_head *bh, ext4_fsblk_t blocknr);

fs/ext4/mballoc.h

@@ -20,6 +20,7 @@
 #include <linux/version.h>
 #include <linux/blkdev.h>
 #include <linux/marker.h>
+#include <linux/mutex.h>
 #include "ext4_jbd2.h"
 #include "ext4.h"
 #include "group.h"
@@ -130,6 +131,7 @@ struct ext4_group_info {
 #ifdef DOUBLE_CHECK
 	void		*bb_bitmap;
 #endif
+	struct rw_semaphore alloc_sem;
 	unsigned short	bb_counters[];
 };
 
@@ -250,6 +252,7 @@ struct ext4_buddy {
 	struct super_block *bd_sb;
 	__u16 bd_blkbits;
 	ext4_group_t bd_group;
+	struct rw_semaphore *alloc_semp;
 };
 #define EXT4_MB_BITMAP(e4b)	((e4b)->bd_bitmap)
 #define EXT4_MB_BUDDY(e4b)	((e4b)->bd_buddy)

fs/ext4/resize.c

@@ -748,6 +748,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 	struct inode *inode = NULL;
 	handle_t *handle;
 	int gdb_off, gdb_num;
+	int num_grp_locked = 0;
 	int err, err2;
 
 	gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
@@ -788,6 +789,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 		}
 	}
 
+
 	if ((err = verify_group_input(sb, input)))
 		goto exit_put;
 
@@ -856,6 +858,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
          * using the new disk blocks.
          */
 
+	num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group);
 	/* Update group descriptor block for new group */
 	gdp = (struct ext4_group_desc *)((char *)primary->b_data +
 					 gdb_off * EXT4_DESC_SIZE(sb));
@@ -872,9 +875,11 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 	 * We can allocate memory for mb_alloc based on the new group
 	 * descriptor
 	 */
-	err = ext4_mb_add_more_groupinfo(sb, input->group, gdp);
-	if (err)
+	err = ext4_mb_add_groupinfo(sb, input->group, gdp);
+	if (err) {
+		ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 		goto exit_journal;
+	}
 
 	/*
 	 * Make the new blocks and inodes valid next.  We do this before
@@ -916,6 +921,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
 
 	/* Update the global fs size fields */
 	sbi->s_groups_count++;
+	ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
 
 	ext4_handle_dirty_metadata(handle, NULL, primary);
 
@@ -1082,45 +1088,6 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 	if ((err = ext4_journal_stop(handle)))
 		goto exit_put;
 
-	/*
-	 * Mark mballoc pages as not up to date so that they will be updated
-	 * next time they are loaded by ext4_mb_load_buddy.
-	 *
-	 * XXX Bad, Bad, BAD!!!  We should not be overloading the
-	 * Uptodate flag, particularly on thte bitmap bh, as way of
-	 * hinting to ext4_mb_load_buddy() that it needs to be
-	 * overloaded.  A user could take a LVM snapshot, then do an
-	 * on-line fsck, and clear the uptodate flag, and this would
-	 * not be a bug in userspace, but a bug in the kernel.  FIXME!!!
-	 */
-	{
-		struct ext4_sb_info *sbi = EXT4_SB(sb);
-		struct inode *inode = sbi->s_buddy_cache;
-		int blocks_per_page;
-		int block;
-		int pnum;
-		struct page *page;
-
-		/* Set buddy page as not up to date */
-		blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize;
-		block = group * 2;
-		pnum = block / blocks_per_page;
-		page = find_get_page(inode->i_mapping, pnum);
-		if (page != NULL) {
-			ClearPageUptodate(page);
-			page_cache_release(page);
-		}
-
-		/* Set bitmap page as not up to date */
-		block++;
-		pnum = block / blocks_per_page;
-		page = find_get_page(inode->i_mapping, pnum);
-		if (page != NULL) {
-			ClearPageUptodate(page);
-			page_cache_release(page);
-		}
-	}
-
 	if (test_opt(sb, DEBUG))
 		printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
 		       ext4_blocks_count(es));