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authorTheodore Ts'o <tytso@mit.edu>2009-04-25 22:53:39 -0400
committerTheodore Ts'o <tytso@mit.edu>2009-04-25 22:53:39 -0400
commit32ed5058ce90024efcd811254b4b1de0468099df (patch)
tree0054cc5c385b4ba02abd95a761ccb01b453ba05f
parent3b9d4ed26680771295d904a6b83e88e620780893 (diff)
ext4: 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(). Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/ext4_sb.h1
-rw-r--r--fs/ext4/resize.c35
-rw-r--r--fs/ext4/super.c1
3 files changed, 20 insertions, 17 deletions
diff --git a/fs/ext4/ext4_sb.h b/fs/ext4/ext4_sb.h
index 4bda2f75d426..2d36223d5f57 100644
--- a/fs/ext4/ext4_sb.h
+++ b/fs/ext4/ext4_sb.h
@@ -72,6 +72,7 @@ struct ext4_sb_info {
72 struct journal_s *s_journal; 72 struct journal_s *s_journal;
73 struct list_head s_orphan; 73 struct list_head s_orphan;
74 struct mutex s_orphan_lock; 74 struct mutex s_orphan_lock;
75 struct mutex s_resize_lock;
75 unsigned long s_commit_interval; 76 unsigned long s_commit_interval;
76 u32 s_max_batch_time; 77 u32 s_max_batch_time;
77 u32 s_min_batch_time; 78 u32 s_min_batch_time;
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 546c7dd869e1..e8ded13b5cb1 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -193,7 +193,7 @@ static int setup_new_group_blocks(struct super_block *sb,
193 if (IS_ERR(handle)) 193 if (IS_ERR(handle))
194 return PTR_ERR(handle); 194 return PTR_ERR(handle);
195 195
196 lock_super(sb); 196 mutex_lock(&sbi->s_resize_lock);
197 if (input->group != sbi->s_groups_count) { 197 if (input->group != sbi->s_groups_count) {
198 err = -EBUSY; 198 err = -EBUSY;
199 goto exit_journal; 199 goto exit_journal;
@@ -302,7 +302,7 @@ exit_bh:
302 brelse(bh); 302 brelse(bh);
303 303
304exit_journal: 304exit_journal:
305 unlock_super(sb); 305 mutex_unlock(&sbi->s_resize_lock);
306 if ((err2 = ext4_journal_stop(handle)) && !err) 306 if ((err2 = ext4_journal_stop(handle)) && !err)
307 err = err2; 307 err = err2;
308 308
@@ -643,11 +643,12 @@ exit_free:
643 * important part is that the new block and inode counts are in the backup 643 * important part is that the new block and inode counts are in the backup
644 * superblocks, and the location of the new group metadata in the GDT backups. 644 * superblocks, and the location of the new group metadata in the GDT backups.
645 * 645 *
646 * We do not need lock_super() for this, because these blocks are not 646 * We do not need take the s_resize_lock for this, because these
647 * otherwise touched by the filesystem code when it is mounted. We don't 647 * blocks are not otherwise touched by the filesystem code when it is
648 * need to worry about last changing from sbi->s_groups_count, because the 648 * mounted. We don't need to worry about last changing from
649 * worst that can happen is that we do not copy the full number of backups 649 * sbi->s_groups_count, because the worst that can happen is that we
650 * at this time. The resize which changed s_groups_count will backup again. 650 * do not copy the full number of backups at this time. The resize
651 * which changed s_groups_count will backup again.
651 */ 652 */
652static void update_backups(struct super_block *sb, 653static void update_backups(struct super_block *sb,
653 int blk_off, char *data, int size) 654 int blk_off, char *data, int size)
@@ -809,7 +810,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
809 goto exit_put; 810 goto exit_put;
810 } 811 }
811 812
812 lock_super(sb); 813 mutex_lock(&sbi->s_resize_lock);
813 if (input->group != sbi->s_groups_count) { 814 if (input->group != sbi->s_groups_count) {
814 ext4_warning(sb, __func__, 815 ext4_warning(sb, __func__,
815 "multiple resizers run on filesystem!"); 816 "multiple resizers run on filesystem!");
@@ -840,7 +841,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
840 /* 841 /*
841 * OK, now we've set up the new group. Time to make it active. 842 * OK, now we've set up the new group. Time to make it active.
842 * 843 *
843 * Current kernels don't lock all allocations via lock_super(), 844 * We do not lock all allocations via s_resize_lock
844 * so we have to be safe wrt. concurrent accesses the group 845 * so we have to be safe wrt. concurrent accesses the group
845 * data. So we need to be careful to set all of the relevant 846 * data. So we need to be careful to set all of the relevant
846 * group descriptor data etc. *before* we enable the group. 847 * group descriptor data etc. *before* we enable the group.
@@ -900,12 +901,12 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
900 * 901 *
901 * The precise rules we use are: 902 * The precise rules we use are:
902 * 903 *
903 * * Writers of s_groups_count *must* hold lock_super 904 * * Writers of s_groups_count *must* hold s_resize_lock
904 * AND 905 * AND
905 * * Writers must perform a smp_wmb() after updating all dependent 906 * * Writers must perform a smp_wmb() after updating all dependent
906 * data and before modifying the groups count 907 * data and before modifying the groups count
907 * 908 *
908 * * Readers must hold lock_super() over the access 909 * * Readers must hold s_resize_lock over the access
909 * OR 910 * OR
910 * * Readers must perform an smp_rmb() after reading the groups count 911 * * Readers must perform an smp_rmb() after reading the groups count
911 * and before reading any dependent data. 912 * and before reading any dependent data.
@@ -948,7 +949,7 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
948 sb->s_dirt = 1; 949 sb->s_dirt = 1;
949 950
950exit_journal: 951exit_journal:
951 unlock_super(sb); 952 mutex_unlock(&sbi->s_resize_lock);
952 if ((err2 = ext4_journal_stop(handle)) && !err) 953 if ((err2 = ext4_journal_stop(handle)) && !err)
953 err = err2; 954 err = err2;
954 if (!err) { 955 if (!err) {
@@ -986,7 +987,7 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
986 987
987 /* We don't need to worry about locking wrt other resizers just 988 /* We don't need to worry about locking wrt other resizers just
988 * yet: we're going to revalidate es->s_blocks_count after 989 * yet: we're going to revalidate es->s_blocks_count after
989 * taking lock_super() below. */ 990 * taking the s_resize_lock below. */
990 o_blocks_count = ext4_blocks_count(es); 991 o_blocks_count = ext4_blocks_count(es);
991 o_groups_count = EXT4_SB(sb)->s_groups_count; 992 o_groups_count = EXT4_SB(sb)->s_groups_count;
992 993
@@ -1056,11 +1057,11 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1056 goto exit_put; 1057 goto exit_put;
1057 } 1058 }
1058 1059
1059 lock_super(sb); 1060 mutex_lock(&EXT4_SB(sb)->s_resize_lock);
1060 if (o_blocks_count != ext4_blocks_count(es)) { 1061 if (o_blocks_count != ext4_blocks_count(es)) {
1061 ext4_warning(sb, __func__, 1062 ext4_warning(sb, __func__,
1062 "multiple resizers run on filesystem!"); 1063 "multiple resizers run on filesystem!");
1063 unlock_super(sb); 1064 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1064 ext4_journal_stop(handle); 1065 ext4_journal_stop(handle);
1065 err = -EBUSY; 1066 err = -EBUSY;
1066 goto exit_put; 1067 goto exit_put;
@@ -1070,14 +1071,14 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
1070 EXT4_SB(sb)->s_sbh))) { 1071 EXT4_SB(sb)->s_sbh))) {
1071 ext4_warning(sb, __func__, 1072 ext4_warning(sb, __func__,
1072 "error %d on journal write access", err); 1073 "error %d on journal write access", err);
1073 unlock_super(sb); 1074 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1074 ext4_journal_stop(handle); 1075 ext4_journal_stop(handle);
1075 goto exit_put; 1076 goto exit_put;
1076 } 1077 }
1077 ext4_blocks_count_set(es, o_blocks_count + add); 1078 ext4_blocks_count_set(es, o_blocks_count + add);
1078 ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh); 1079 ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
1079 sb->s_dirt = 1; 1080 sb->s_dirt = 1;
1080 unlock_super(sb); 1081 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1081 ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count, 1082 ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1082 o_blocks_count + add); 1083 o_blocks_count + add);
1083 /* We add the blocks to the bitmap and set the group need init bit */ 1084 /* We add the blocks to the bitmap and set the group need init bit */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7f43fde9554b..1fbf0906ae2e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2646,6 +2646,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
2646#endif 2646#endif
2647 INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */ 2647 INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */
2648 mutex_init(&sbi->s_orphan_lock); 2648 mutex_init(&sbi->s_orphan_lock);
2649 mutex_init(&sbi->s_resize_lock);
2649 2650
2650 sb->s_root = NULL; 2651 sb->s_root = NULL;
2651 2652