From 96d2a495c25d525873529b736cdb63ad502b101c Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Mon, 14 Dec 2009 13:01:05 -0600 Subject: [PATCH] ext3: Replace lock/unlock_super() with an explicit lock for resizing Use a separate lock to protect s_groups_count and the other block group descriptors which get changed via an on-line resize operation, so we can stop overloading the use of lock_super(). Port of ext4 commit 32ed5058ce90024efcd811254b4b1de0468099df by Theodore Ts'o . CC: Theodore Ts'o Signed-off-by: Eric Sandeen Signed-off-by: Jan Kara --- fs/ext3/resize.c | 35 ++++++++++++++++++----------------- fs/ext3/super.c | 1 + include/linux/ext3_fs_sb.h | 1 + 3 files changed, 20 insertions(+), 17 deletions(-) diff --git a/fs/ext3/resize.c b/fs/ext3/resize.c index 5f83b6179178..54351ac7cef9 100644 --- a/fs/ext3/resize.c +++ b/fs/ext3/resize.c @@ -209,7 +209,7 @@ static int setup_new_group_blocks(struct super_block *sb, if (IS_ERR(handle)) return PTR_ERR(handle); - lock_super(sb); + mutex_lock(&sbi->s_resize_lock); if (input->group != sbi->s_groups_count) { err = -EBUSY; goto exit_journal; @@ -324,7 +324,7 @@ exit_bh: brelse(bh); exit_journal: - unlock_super(sb); + mutex_unlock(&sbi->s_resize_lock); if ((err2 = ext3_journal_stop(handle)) && !err) err = err2; @@ -662,11 +662,12 @@ exit_free: * important part is that the new block and inode counts are in the backup * superblocks, and the location of the new group metadata in the GDT backups. * - * We do not need lock_super() for this, because these blocks are not - * otherwise touched by the filesystem code when it is mounted. We don't - * need to worry about last changing from sbi->s_groups_count, because the - * worst that can happen is that we do not copy the full number of backups - * at this time. The resize which changed s_groups_count will backup again. + * We do not need take the s_resize_lock for this, because these + * blocks are not otherwise touched by the filesystem code when it is + * mounted. We don't need to worry about last changing from + * sbi->s_groups_count, because the worst that can happen is that we + * do not copy the full number of backups at this time. The resize + * which changed s_groups_count will backup again. */ static void update_backups(struct super_block *sb, int blk_off, char *data, int size) @@ -825,7 +826,7 @@ int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input) goto exit_put; } - lock_super(sb); + mutex_lock(&sbi->s_resize_lock); if (input->group != sbi->s_groups_count) { ext3_warning(sb, __func__, "multiple resizers run on filesystem!"); @@ -856,7 +857,7 @@ int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input) /* * OK, now we've set up the new group. Time to make it active. * - * Current kernels don't lock all allocations via lock_super(), + * We do not lock all allocations via s_resize_lock * so we have to be safe wrt. concurrent accesses the group * data. So we need to be careful to set all of the relevant * group descriptor data etc. *before* we enable the group. @@ -900,12 +901,12 @@ int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input) * * The precise rules we use are: * - * * Writers of s_groups_count *must* hold lock_super + * * Writers of s_groups_count *must* hold s_resize_lock * AND * * Writers must perform a smp_wmb() after updating all dependent * data and before modifying the groups count * - * * Readers must hold lock_super() over the access + * * Readers must hold s_resize_lock over the access * OR * * Readers must perform an smp_rmb() after reading the groups count * and before reading any dependent data. @@ -936,7 +937,7 @@ int ext3_group_add(struct super_block *sb, struct ext3_new_group_data *input) ext3_journal_dirty_metadata(handle, sbi->s_sbh); exit_journal: - unlock_super(sb); + mutex_unlock(&sbi->s_resize_lock); if ((err2 = ext3_journal_stop(handle)) && !err) err = err2; if (!err) { @@ -973,7 +974,7 @@ int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es, /* We don't need to worry about locking wrt other resizers just * yet: we're going to revalidate es->s_blocks_count after - * taking lock_super() below. */ + * taking the s_resize_lock below. */ o_blocks_count = le32_to_cpu(es->s_blocks_count); o_groups_count = EXT3_SB(sb)->s_groups_count; @@ -1045,11 +1046,11 @@ int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es, goto exit_put; } - lock_super(sb); + mutex_lock(&EXT3_SB(sb)->s_resize_lock); if (o_blocks_count != le32_to_cpu(es->s_blocks_count)) { ext3_warning(sb, __func__, "multiple resizers run on filesystem!"); - unlock_super(sb); + mutex_unlock(&EXT3_SB(sb)->s_resize_lock); ext3_journal_stop(handle); err = -EBUSY; goto exit_put; @@ -1059,13 +1060,13 @@ int ext3_group_extend(struct super_block *sb, struct ext3_super_block *es, EXT3_SB(sb)->s_sbh))) { ext3_warning(sb, __func__, "error %d on journal write access", err); - unlock_super(sb); + mutex_unlock(&EXT3_SB(sb)->s_resize_lock); ext3_journal_stop(handle); goto exit_put; } es->s_blocks_count = cpu_to_le32(o_blocks_count + add); ext3_journal_dirty_metadata(handle, EXT3_SB(sb)->s_sbh); - unlock_super(sb); + mutex_unlock(&EXT3_SB(sb)->s_resize_lock); ext3_debug("freeing blocks %lu through "E3FSBLK"\n", o_blocks_count, o_blocks_count + add); ext3_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks); diff --git a/fs/ext3/super.c b/fs/ext3/super.c index 97dd3828384c..afa2b569da10 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -1929,6 +1929,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent) #endif INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */ mutex_init(&sbi->s_orphan_lock); + mutex_init(&sbi->s_resize_lock); sb->s_root = NULL; diff --git a/include/linux/ext3_fs_sb.h b/include/linux/ext3_fs_sb.h index dd61d83026a0..258088ab3c6b 100644 --- a/include/linux/ext3_fs_sb.h +++ b/include/linux/ext3_fs_sb.h @@ -73,6 +73,7 @@ struct ext3_sb_info { struct journal_s * s_journal; struct list_head s_orphan; struct mutex s_orphan_lock; + struct mutex s_resize_lock; unsigned long s_commit_interval; struct block_device *journal_bdev; #ifdef CONFIG_JBD_DEBUG -- 2.30.2