As Jan pointed out[1], as of commit 
81378da64de ("jbd2: mark the
transaction context with the scope GFP_NOFS context") we use
memalloc_nofs_{save,restore}() while a jbd2 handle is active.  So
ext4_kvmalloc() so we can call allocate using GFP_NOFS is no longer
necessary.
[1] https://lore.kernel.org/r/
20200109100007.GC27035@quack2.suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200116155031.266620-1-tytso@mit.edu
Reviewed-by: Jan Kara <jack@suse.cz>
 extern int ext4_seq_options_show(struct seq_file *seq, void *offset);
 extern int ext4_calculate_overhead(struct super_block *sb);
 extern void ext4_superblock_csum_set(struct super_block *sb);
-extern void *ext4_kvmalloc(size_t size, gfp_t flags);
 extern int ext4_alloc_flex_bg_array(struct super_block *sb,
                                    ext4_group_t ngroup);
 extern const char *ext4_decode_error(struct super_block *sb, int errno,
 
        if (unlikely(err))
                goto errout;
 
-       n_group_desc = ext4_kvmalloc((gdb_num + 1) *
-                                    sizeof(struct buffer_head *),
-                                    GFP_NOFS);
+       n_group_desc = kvmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
+                               GFP_KERNEL);
        if (!n_group_desc) {
                err = -ENOMEM;
                ext4_warning(sb, "not enough memory for %lu groups",
        gdb_bh = ext4_sb_bread(sb, gdblock, 0);
        if (IS_ERR(gdb_bh))
                return PTR_ERR(gdb_bh);
-       n_group_desc = ext4_kvmalloc((gdb_num + 1) *
-                                    sizeof(struct buffer_head *),
-                                    GFP_NOFS);
+       n_group_desc = kvmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
+                               GFP_KERNEL);
        if (!n_group_desc) {
                brelse(gdb_bh);
                err = -ENOMEM;
 
        es->s_checksum = ext4_superblock_csum(sb, es);
 }
 
-void *ext4_kvmalloc(size_t size, gfp_t flags)
-{
-       void *ret;
-
-       ret = kmalloc(size, flags | __GFP_NOWARN);
-       if (!ret)
-               ret = __vmalloc(size, flags, PAGE_KERNEL);
-       return ret;
-}
-
 ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
                               struct ext4_group_desc *bg)
 {
 
        if (!ce)
                return NULL;
 
-       ea_data = ext4_kvmalloc(value_len, GFP_NOFS);
+       ea_data = kvmalloc(value_len, GFP_KERNEL);
        if (!ea_data) {
                mb_cache_entry_put(ea_inode_cache, ce);
                return NULL;