Commit c5ca7c76 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Fallback to vmalloc if kmalloc can't allocate s_flex_groups array 



For very large filesystems, the s_flex_groups array can get quite big.
For example, a filesystem that can be resized up to 16TB will have
8192 flex groups (assuming the default flex_bg size of 16), so the
array is 96k, which is *very* marginal for kmalloc().  On the other
hand, a 160GB filesystem without the resize_inode feature will only
require 960 bytes.  So we try to allocate the array first using
kmalloc(), and if that fails, we'll try to use vmalloc() instead.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 29fa89d0

fs/ext4/super.c

+19 −3
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/string.h>

#include <linux/fs.h>

#include <linux/time.h>

#include <linux/vmalloc.h>

#include <linux/jbd2.h>

#include <linux/slab.h>

#include <linux/init.h>
@@ -586,6 +587,9 @@ static void ext4_put_super(struct super_block *sb) 
	for (i = 0; i < sbi->s_gdb_count; i++)

		brelse(sbi->s_group_desc[i]);

	kfree(sbi->s_group_desc);

	if (is_vmalloc_addr(sbi->s_flex_groups))

		vfree(sbi->s_flex_groups);

	else

		kfree(sbi->s_flex_groups);

	percpu_counter_destroy(&sbi->s_freeblocks_counter);

	percpu_counter_destroy(&sbi->s_freeinodes_counter);
@@ -1620,6 +1624,7 @@ static int ext4_fill_flex_info(struct super_block *sb) 
	ext4_group_t flex_group_count;

	ext4_group_t flex_group;

	int groups_per_flex = 0;

	size_t size;

	int i;



	if (!sbi->s_es->s_log_groups_per_flex) {
@@ -1634,8 +1639,13 @@ static int ext4_fill_flex_info(struct super_block *sb) 
	flex_group_count = ((sbi->s_groups_count + groups_per_flex - 1) +

			((le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) + 1) <<

			      EXT4_DESC_PER_BLOCK_BITS(sb))) / groups_per_flex;

	sbi->s_flex_groups = kzalloc(flex_group_count *

				     sizeof(struct flex_groups), GFP_KERNEL);

	size = flex_group_count * sizeof(struct flex_groups);

	sbi->s_flex_groups = kzalloc(size, GFP_KERNEL);

	if (sbi->s_flex_groups == NULL) {

		sbi->s_flex_groups = vmalloc(size);

		if (sbi->s_flex_groups)

			memset(sbi->s_flex_groups, 0, size);

	}

	if (sbi->s_flex_groups == NULL) {

		printk(KERN_ERR "EXT4-fs: not enough memory for "

				"%u flex groups\n", flex_group_count);
@@ -2842,6 +2852,12 @@ failed_mount4: 
		sbi->s_journal = NULL;

	}

failed_mount3:

	if (sbi->s_flex_groups) {

		if (is_vmalloc_addr(sbi->s_flex_groups))

			vfree(sbi->s_flex_groups);

		else

			kfree(sbi->s_flex_groups);

	}

	percpu_counter_destroy(&sbi->s_freeblocks_counter);

	percpu_counter_destroy(&sbi->s_freeinodes_counter);

	percpu_counter_destroy(&sbi->s_dirs_counter);

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