1 files changed, 194 insertions, 137 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4079605d437a..19f2e7c77be8 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -365,12 +365,12 @@ static void __save_error_info(struct super_block *sb, const char *func,
 		return;
 	es->s_state |= cpu_to_le16(EXT4_ERROR_FS);
 	ext4_update_tstamp(es, s_last_error_time);
-	strncpy(es->s_last_error_func, func, sizeof(es->s_last_error_func));
+	strscpy_pad(es->s_last_error_func, func, sizeof(es->s_last_error_func));
 	es->s_last_error_line = cpu_to_le32(line);
 	if (!es->s_first_error_time) {
 		es->s_first_error_time = es->s_last_error_time;
 		es->s_first_error_time_hi = es->s_last_error_time_hi;
-		strncpy(es->s_first_error_func, func,
+		strscpy_pad(es->s_first_error_func, func,
 			sizeof(es->s_first_error_func));
 		es->s_first_error_line = cpu_to_le32(line);
 		es->s_first_error_ino = es->s_last_error_ino;
@@ -389,7 +389,8 @@ static void save_error_info(struct super_block *sb, const char *func,
 			    unsigned int line)
 {
 	__save_error_info(sb, func, line);
-	ext4_commit_super(sb, 1);
+	if (!bdev_read_only(sb->s_bdev))
+		ext4_commit_super(sb, 1);
 }
 
 /*
@@ -970,6 +971,8 @@ static void ext4_put_super(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
+	struct buffer_head **group_desc;
+	struct flex_groups **flex_groups;
 	int aborted = 0;
 	int i, err;
 
@@ -1000,15 +1003,23 @@ static void ext4_put_super(struct super_block *sb)
 	if (!sb_rdonly(sb))
 		ext4_commit_super(sb, 1);
 
+	rcu_read_lock();
+	group_desc = rcu_dereference(sbi->s_group_desc);
 	for (i = 0; i < sbi->s_gdb_count; i++)
-		brelse(sbi->s_group_desc[i]);
-	kvfree(sbi->s_group_desc);
-	kvfree(sbi->s_flex_groups);
+		brelse(group_desc[i]);
+	kvfree(group_desc);
+	flex_groups = rcu_dereference(sbi->s_flex_groups);
+	if (flex_groups) {
+		for (i = 0; i < sbi->s_flex_groups_allocated; i++)
+			kvfree(flex_groups[i]);
+		kvfree(flex_groups);
+	}
+	rcu_read_unlock();
 	percpu_counter_destroy(&sbi->s_freeclusters_counter);
 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
 	percpu_counter_destroy(&sbi->s_dirs_counter);
 	percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
-	percpu_free_rwsem(&sbi->s_journal_flag_rwsem);
+	percpu_free_rwsem(&sbi->s_writepages_rwsem);
 #ifdef CONFIG_QUOTA
 	for (i = 0; i < EXT4_MAXQUOTAS; i++)
 		kfree(get_qf_name(sb, sbi, i));
@@ -1876,6 +1887,13 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 			arg = JBD2_DEFAULT_MAX_COMMIT_AGE;
 		sbi->s_commit_interval = HZ * arg;
 	} else if (token == Opt_debug_want_extra_isize) {
+		if ((arg & 1) ||
+		    (arg < 4) ||
+		    (arg > (sbi->s_inode_size - EXT4_GOOD_OLD_INODE_SIZE))) {
+			ext4_msg(sb, KERN_ERR,
+				 "Invalid want_extra_isize %d", arg);
+			return -1;
+		}
 		sbi->s_want_extra_isize = arg;
 	} else if (token == Opt_max_batch_time) {
 		sbi->s_max_batch_time = arg;
@@ -2005,6 +2023,16 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 #endif
 	} else if (token == Opt_dax) {
 #ifdef CONFIG_FS_DAX
+		if (is_remount && test_opt(sb, DAX)) {
+			ext4_msg(sb, KERN_ERR, "can't mount with "
+				"both data=journal and dax");
+			return -1;
+		}
+		if (is_remount && !(sbi->s_mount_opt & EXT4_MOUNT_DAX)) {
+			ext4_msg(sb, KERN_ERR, "can't change "
+					"dax mount option while remounting");
+			return -1;
+		}
 		ext4_msg(sb, KERN_WARNING,
 		"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
 		sbi->s_mount_opt |= m->mount_opt;
@@ -2265,6 +2293,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
 		ext4_msg(sb, KERN_ERR, "revision level too high, "
 			 "forcing read-only mode");
 		err = -EROFS;
+		goto done;
 	}
 	if (read_only)
 		goto done;
@@ -2314,8 +2343,8 @@ done:
 int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct flex_groups *new_groups;
-	int size;
+	struct flex_groups **old_groups, **new_groups;
+	int size, i, j;
 
 	if (!sbi->s_log_groups_per_flex)
 		return 0;
@@ -2324,22 +2353,37 @@ int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup)
 	if (size <= sbi->s_flex_groups_allocated)
 		return 0;
 
-	size = roundup_pow_of_two(size * sizeof(struct flex_groups));
-	new_groups = kvzalloc(size, GFP_KERNEL);
+	new_groups = kvzalloc(roundup_pow_of_two(size *
+			      sizeof(*sbi->s_flex_groups)), GFP_KERNEL);
 	if (!new_groups) {
-		ext4_msg(sb, KERN_ERR, "not enough memory for %d flex groups",
-			 size / (int) sizeof(struct flex_groups));
+		ext4_msg(sb, KERN_ERR,
+			 "not enough memory for %d flex group pointers", size);
 		return -ENOMEM;
 	}
-
-	if (sbi->s_flex_groups) {
-		memcpy(new_groups, sbi->s_flex_groups,
-		       (sbi->s_flex_groups_allocated *
-			sizeof(struct flex_groups)));
-		kvfree(sbi->s_flex_groups);
+	for (i = sbi->s_flex_groups_allocated; i < size; i++) {
+		new_groups[i] = kvzalloc(roundup_pow_of_two(
+					 sizeof(struct flex_groups)),
+					 GFP_KERNEL);
+		if (!new_groups[i]) {
+			for (j = sbi->s_flex_groups_allocated; j < i; j++)
+				kvfree(new_groups[j]);
+			kvfree(new_groups);
+			ext4_msg(sb, KERN_ERR,
+				 "not enough memory for %d flex groups", size);
+			return -ENOMEM;
+		}
 	}
-	sbi->s_flex_groups = new_groups;
-	sbi->s_flex_groups_allocated = size / sizeof(struct flex_groups);
+	rcu_read_lock();
+	old_groups = rcu_dereference(sbi->s_flex_groups);
+	if (old_groups)
+		memcpy(new_groups, old_groups,
+		       (sbi->s_flex_groups_allocated *
+			sizeof(struct flex_groups *)));
+	rcu_read_unlock();
+	rcu_assign_pointer(sbi->s_flex_groups, new_groups);
+	sbi->s_flex_groups_allocated = size;
+	if (old_groups)
+		ext4_kvfree_array_rcu(old_groups);
 	return 0;
 }
 
@@ -2347,6 +2391,7 @@ static int ext4_fill_flex_info(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_group_desc *gdp = NULL;
+	struct flex_groups *fg;
 	ext4_group_t flex_group;
 	int i, err;
 
@@ -2364,12 +2409,11 @@ static int ext4_fill_flex_info(struct super_block *sb)
 		gdp = ext4_get_group_desc(sb, i, NULL);
 
 		flex_group = ext4_flex_group(sbi, i);
-		atomic_add(ext4_free_inodes_count(sb, gdp),
-			   &sbi->s_flex_groups[flex_group].free_inodes);
+		fg = sbi_array_rcu_deref(sbi, s_flex_groups, flex_group);
+		atomic_add(ext4_free_inodes_count(sb, gdp), &fg->free_inodes);
 		atomic64_add(ext4_free_group_clusters(sb, gdp),
-			     &sbi->s_flex_groups[flex_group].free_clusters);
-		atomic_add(ext4_used_dirs_count(sb, gdp),
-			   &sbi->s_flex_groups[flex_group].used_dirs);
+			     &fg->free_clusters);
+		atomic_add(ext4_used_dirs_count(sb, gdp), &fg->used_dirs);
 	}
 
 	return 1;
@@ -2943,17 +2987,11 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly)
 		return 0;
 	}
 
-#ifndef CONFIG_QUOTA
-	if (ext4_has_feature_quota(sb) && !readonly) {
-		ext4_msg(sb, KERN_ERR,
-			 "Filesystem with quota feature cannot be mounted RDWR "
-			 "without CONFIG_QUOTA");
-		return 0;
-	}
-	if (ext4_has_feature_project(sb) && !readonly) {
+#if !IS_ENABLED(CONFIG_QUOTA) || !IS_ENABLED(CONFIG_QFMT_V2)
+	if (!readonly && (ext4_has_feature_quota(sb) ||
+			  ext4_has_feature_project(sb))) {
 		ext4_msg(sb, KERN_ERR,
-			 "Filesystem with project quota feature cannot be mounted RDWR "
-			 "without CONFIG_QUOTA");
+			 "The kernel was not built with CONFIG_QUOTA and CONFIG_QFMT_V2");
 		return 0;
 	}
 #endif  /* CONFIG_QUOTA */
@@ -3524,7 +3562,8 @@ int ext4_calculate_overhead(struct super_block *sb)
 	 */
 	if (sbi->s_journal && !sbi->journal_bdev)
 		overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen);
-	else if (ext4_has_feature_journal(sb) && !sbi->s_journal) {
+	else if (ext4_has_feature_journal(sb) && !sbi->s_journal && j_inum) {
+		/* j_inum for internal journal is non-zero */
 		j_inode = ext4_get_journal_inode(sb, j_inum);
 		if (j_inode) {
 			j_blocks = j_inode->i_size >> sb->s_blocksize_bits;
@@ -3540,37 +3579,6 @@ int ext4_calculate_overhead(struct super_block *sb)
 	return 0;
 }
 
-static void ext4_clamp_want_extra_isize(struct super_block *sb)
-{
-	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct ext4_super_block *es = sbi->s_es;
-
-	/* determine the minimum size of new large inodes, if present */
-	if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE &&
-	    sbi->s_want_extra_isize == 0) {
-		sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
-						     EXT4_GOOD_OLD_INODE_SIZE;
-		if (ext4_has_feature_extra_isize(sb)) {
-			if (sbi->s_want_extra_isize <
-			    le16_to_cpu(es->s_want_extra_isize))
-				sbi->s_want_extra_isize =
-					le16_to_cpu(es->s_want_extra_isize);
-			if (sbi->s_want_extra_isize <
-			    le16_to_cpu(es->s_min_extra_isize))
-				sbi->s_want_extra_isize =
-					le16_to_cpu(es->s_min_extra_isize);
-		}
-	}
-	/* Check if enough inode space is available */
-	if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
-							sbi->s_inode_size) {
-		sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
-						       EXT4_GOOD_OLD_INODE_SIZE;
-		ext4_msg(sb, KERN_INFO,
-			 "required extra inode space not available");
-	}
-}
-
 static void ext4_set_resv_clusters(struct super_block *sb)
 {
 	ext4_fsblk_t resv_clusters;
@@ -3605,9 +3613,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev);
 	char *orig_data = kstrdup(data, GFP_KERNEL);
-	struct buffer_head *bh;
+	struct buffer_head *bh, **group_desc;
 	struct ext4_super_block *es = NULL;
 	struct ext4_sb_info *sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
+	struct flex_groups **flex_groups;
 	ext4_fsblk_t block;
 	ext4_fsblk_t sb_block = get_sb_block(&data);
 	ext4_fsblk_t logical_sb_block;
@@ -3778,6 +3787,75 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 */
 	sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
 
+	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
+	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
+	    blocksize > EXT4_MAX_BLOCK_SIZE) {
+		ext4_msg(sb, KERN_ERR,
+		       "Unsupported filesystem blocksize %d (%d log_block_size)",
+			 blocksize, le32_to_cpu(es->s_log_block_size));
+		goto failed_mount;
+	}
+
+	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
+		sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
+		sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
+	} else {
+		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
+		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
+		if (sbi->s_first_ino < EXT4_GOOD_OLD_FIRST_INO) {
+			ext4_msg(sb, KERN_ERR, "invalid first ino: %u",
+				 sbi->s_first_ino);
+			goto failed_mount;
+		}
+		if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
+		    (!is_power_of_2(sbi->s_inode_size)) ||
+		    (sbi->s_inode_size > blocksize)) {
+			ext4_msg(sb, KERN_ERR,
+			       "unsupported inode size: %d",
+			       sbi->s_inode_size);
+			ext4_msg(sb, KERN_ERR, "blocksize: %d", blocksize);
+			goto failed_mount;
+		}
+		/*
+		 * i_atime_extra is the last extra field available for
+		 * [acm]times in struct ext4_inode. Checking for that
+		 * field should suffice to ensure we have extra space
+		 * for all three.
+		 */
+		if (sbi->s_inode_size >= offsetof(struct ext4_inode, i_atime_extra) +
+			sizeof(((struct ext4_inode *)0)->i_atime_extra)) {
+			sb->s_time_gran = 1;
+		} else {
+			sb->s_time_gran = NSEC_PER_SEC;
+		}
+	}
+	if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
+		sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
+			EXT4_GOOD_OLD_INODE_SIZE;
+		if (ext4_has_feature_extra_isize(sb)) {
+			unsigned v, max = (sbi->s_inode_size -
+					   EXT4_GOOD_OLD_INODE_SIZE);
+
+			v = le16_to_cpu(es->s_want_extra_isize);
+			if (v > max) {
+				ext4_msg(sb, KERN_ERR,
+					 "bad s_want_extra_isize: %d", v);
+				goto failed_mount;
+			}
+			if (sbi->s_want_extra_isize < v)
+				sbi->s_want_extra_isize = v;
+
+			v = le16_to_cpu(es->s_min_extra_isize);
+			if (v > max) {
+				ext4_msg(sb, KERN_ERR,
+					 "bad s_min_extra_isize: %d", v);
+				goto failed_mount;
+			}
+			if (sbi->s_want_extra_isize < v)
+				sbi->s_want_extra_isize = v;
+		}
+	}
+
 	if (sbi->s_es->s_mount_opts[0]) {
 		char *s_mount_opts = kstrndup(sbi->s_es->s_mount_opts,
 					      sizeof(sbi->s_es->s_mount_opts),
@@ -3936,14 +4014,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	if (!ext4_feature_set_ok(sb, (sb_rdonly(sb))))
 		goto failed_mount;
 
-	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
-	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
-	    blocksize > EXT4_MAX_BLOCK_SIZE) {
-		ext4_msg(sb, KERN_ERR,
-		       "Unsupported filesystem blocksize %d (%d log_block_size)",
-			 blocksize, le32_to_cpu(es->s_log_block_size));
-		goto failed_mount;
-	}
 	if (le32_to_cpu(es->s_log_block_size) >
 	    (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
 		ext4_msg(sb, KERN_ERR,
@@ -4016,29 +4086,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 						      has_huge_files);
 	sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits, has_huge_files);
 
-	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
-		sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
-		sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
-	} else {
-		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
-		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
-		if (sbi->s_first_ino < EXT4_GOOD_OLD_FIRST_INO) {
-			ext4_msg(sb, KERN_ERR, "invalid first ino: %u",
-				 sbi->s_first_ino);
-			goto failed_mount;
-		}
-		if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
-		    (!is_power_of_2(sbi->s_inode_size)) ||
-		    (sbi->s_inode_size > blocksize)) {
-			ext4_msg(sb, KERN_ERR,
-			       "unsupported inode size: %d",
-			       sbi->s_inode_size);
-			goto failed_mount;
-		}
-		if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE)
-			sb->s_time_gran = 1 << (EXT4_EPOCH_BITS - 2);
-	}
-
 	sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
 	if (ext4_has_feature_64bit(sb)) {
 		if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE_64BIT ||
@@ -4061,7 +4108,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	if (sbi->s_inodes_per_group < sbi->s_inodes_per_block ||
 	    sbi->s_inodes_per_group > blocksize * 8) {
 		ext4_msg(sb, KERN_ERR, "invalid inodes per group: %lu\n",
-			 sbi->s_blocks_per_group);
+			 sbi->s_inodes_per_group);
 		goto failed_mount;
 	}
 	sbi->s_itb_per_group = sbi->s_inodes_per_group /
@@ -4190,9 +4237,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			EXT4_BLOCKS_PER_GROUP(sb) - 1);
 	do_div(blocks_count, EXT4_BLOCKS_PER_GROUP(sb));
 	if (blocks_count > ((uint64_t)1<<32) - EXT4_DESC_PER_BLOCK(sb)) {
-		ext4_msg(sb, KERN_WARNING, "groups count too large: %u "
+		ext4_msg(sb, KERN_WARNING, "groups count too large: %llu "
 		       "(block count %llu, first data block %u, "
-		       "blocks per group %lu)", sbi->s_groups_count,
+		       "blocks per group %lu)", blocks_count,
 		       ext4_blocks_count(es),
 		       le32_to_cpu(es->s_first_data_block),
 		       EXT4_BLOCKS_PER_GROUP(sb));
@@ -4220,9 +4267,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			goto failed_mount;
 		}
 	}
-	sbi->s_group_desc = kvmalloc_array(db_count,
-					   sizeof(struct buffer_head *),
-					   GFP_KERNEL);
+	rcu_assign_pointer(sbi->s_group_desc,
+			   kvmalloc_array(db_count,
+					  sizeof(struct buffer_head *),
+					  GFP_KERNEL));
 	if (sbi->s_group_desc == NULL) {
 		ext4_msg(sb, KERN_ERR, "not enough memory");
 		ret = -ENOMEM;
@@ -4234,18 +4282,23 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	/* Pre-read the descriptors into the buffer cache */
 	for (i = 0; i < db_count; i++) {
 		block = descriptor_loc(sb, logical_sb_block, i);
-		sb_breadahead(sb, block);
+		sb_breadahead_unmovable(sb, block);
 	}
 
 	for (i = 0; i < db_count; i++) {
+		struct buffer_head *bh;
+
 		block = descriptor_loc(sb, logical_sb_block, i);
-		sbi->s_group_desc[i] = sb_bread_unmovable(sb, block);
-		if (!sbi->s_group_desc[i]) {
+		bh = sb_bread_unmovable(sb, block);
+		if (!bh) {
 			ext4_msg(sb, KERN_ERR,
 			       "can't read group descriptor %d", i);
 			db_count = i;
 			goto failed_mount2;
 		}
+		rcu_read_lock();
+		rcu_dereference(sbi->s_group_desc)[i] = bh;
+		rcu_read_unlock();
 	}
 	sbi->s_gdb_count = db_count;
 	if (!ext4_check_descriptors(sb, logical_sb_block, &first_not_zeroed)) {
@@ -4486,8 +4539,6 @@ no_journal:
 	} else if (ret)
 		goto failed_mount4a;
 
-	ext4_clamp_want_extra_isize(sb);
-
 	ext4_set_resv_clusters(sb);
 
 	err = ext4_setup_system_zone(sb);
@@ -4525,7 +4576,7 @@ no_journal:
 		err = percpu_counter_init(&sbi->s_dirtyclusters_counter, 0,
 					  GFP_KERNEL);
 	if (!err)
-		err = percpu_init_rwsem(&sbi->s_journal_flag_rwsem);
+		err = percpu_init_rwsem(&sbi->s_writepages_rwsem);
 
 	if (err) {
 		ext4_msg(sb, KERN_ERR, "insufficient memory");
@@ -4613,13 +4664,19 @@ failed_mount7:
 	ext4_unregister_li_request(sb);
 failed_mount6:
 	ext4_mb_release(sb);
-	if (sbi->s_flex_groups)
-		kvfree(sbi->s_flex_groups);
+	rcu_read_lock();
+	flex_groups = rcu_dereference(sbi->s_flex_groups);
+	if (flex_groups) {
+		for (i = 0; i < sbi->s_flex_groups_allocated; i++)
+			kvfree(flex_groups[i]);
+		kvfree(flex_groups);
+	}
+	rcu_read_unlock();
 	percpu_counter_destroy(&sbi->s_freeclusters_counter);
 	percpu_counter_destroy(&sbi->s_freeinodes_counter);
 	percpu_counter_destroy(&sbi->s_dirs_counter);
 	percpu_counter_destroy(&sbi->s_dirtyclusters_counter);
-	percpu_free_rwsem(&sbi->s_journal_flag_rwsem);
+	percpu_free_rwsem(&sbi->s_writepages_rwsem);
 failed_mount5:
 	ext4_ext_release(sb);
 	ext4_release_system_zone(sb);
@@ -4648,9 +4705,12 @@ failed_mount3:
 	if (sbi->s_mmp_tsk)
 		kthread_stop(sbi->s_mmp_tsk);
 failed_mount2:
+	rcu_read_lock();
+	group_desc = rcu_dereference(sbi->s_group_desc);
 	for (i = 0; i < db_count; i++)
-		brelse(sbi->s_group_desc[i]);
-	kvfree(sbi->s_group_desc);
+		brelse(group_desc[i]);
+	kvfree(group_desc);
+	rcu_read_unlock();
 failed_mount:
 	if (sbi->s_chksum_driver)
 		crypto_free_shash(sbi->s_chksum_driver);
@@ -5275,8 +5335,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		goto restore_opts;
 	}
 
-	ext4_clamp_want_extra_isize(sb);
-
 	if ((old_opts.s_mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) ^
 	    test_opt(sb, JOURNAL_CHECKSUM)) {
 		ext4_msg(sb, KERN_ERR, "changing journal_checksum "
@@ -5297,12 +5355,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 			err = -EINVAL;
 			goto restore_opts;
 		}
-		if (test_opt(sb, DAX)) {
-			ext4_msg(sb, KERN_ERR, "can't mount with "
-				 "both data=journal and dax");
-			err = -EINVAL;
-			goto restore_opts;
-		}
 	} else if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_ORDERED_DATA) {
 		if (test_opt(sb, JOURNAL_ASYNC_COMMIT)) {
 			ext4_msg(sb, KERN_ERR, "can't mount with "
@@ -5318,12 +5370,6 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 		goto restore_opts;
 	}
 
-	if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX) {
-		ext4_msg(sb, KERN_WARNING, "warning: refusing change of "
-			"dax flag with busy inodes while remounting");
-		sbi->s_mount_opt ^= EXT4_MOUNT_DAX;
-	}
-
 	if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
 		ext4_abort(sb, "Abort forced by user");
 
@@ -5514,9 +5560,15 @@ static int ext4_statfs_project(struct super_block *sb,
 		return PTR_ERR(dquot);
 	spin_lock(&dquot->dq_dqb_lock);
 
-	limit = (dquot->dq_dqb.dqb_bsoftlimit ?
-		 dquot->dq_dqb.dqb_bsoftlimit :
-		 dquot->dq_dqb.dqb_bhardlimit) >> sb->s_blocksize_bits;
+	limit = 0;
+	if (dquot->dq_dqb.dqb_bsoftlimit &&
+	    (!limit || dquot->dq_dqb.dqb_bsoftlimit < limit))
+		limit = dquot->dq_dqb.dqb_bsoftlimit;
+	if (dquot->dq_dqb.dqb_bhardlimit &&
+	    (!limit || dquot->dq_dqb.dqb_bhardlimit < limit))
+		limit = dquot->dq_dqb.dqb_bhardlimit;
+	limit >>= sb->s_blocksize_bits;
+
 	if (limit && buf->f_blocks > limit) {
 		curblock = (dquot->dq_dqb.dqb_curspace +
 			    dquot->dq_dqb.dqb_rsvspace) >> sb->s_blocksize_bits;
@@ -5526,9 +5578,14 @@ static int ext4_statfs_project(struct super_block *sb,
 			 (buf->f_blocks - curblock) : 0;
 	}
 
-	limit = dquot->dq_dqb.dqb_isoftlimit ?
-		dquot->dq_dqb.dqb_isoftlimit :
-		dquot->dq_dqb.dqb_ihardlimit;
+	limit = 0;
+	if (dquot->dq_dqb.dqb_isoftlimit &&
+	    (!limit || dquot->dq_dqb.dqb_isoftlimit < limit))
+		limit = dquot->dq_dqb.dqb_isoftlimit;
+	if (dquot->dq_dqb.dqb_ihardlimit &&
+	    (!limit || dquot->dq_dqb.dqb_ihardlimit < limit))
+		limit = dquot->dq_dqb.dqb_ihardlimit;
+
 	if (limit && buf->f_files > limit) {
 		buf->f_files = limit;
 		buf->f_ffree =