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Commit 9651e6b2 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Theodore Ts'o
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ext4: handle the rest of ext4_mb_load_buddy() ENOMEM errors 



I've got another report about breaking ext4 by ENOMEM error returned from
ext4_mb_load_buddy() caused by memory shortage in memory cgroup.
This time inside ext4_discard_preallocations().

This patch replaces ext4_error() with ext4_warning() where errors returned
from ext4_mb_load_buddy() are not fatal and handled by caller:
* ext4_mb_discard_group_preallocations() - called before generating ENOSPC,
  we'll try to discard other group or return ENOSPC into user-space.
* ext4_trim_all_free() - just stop trimming and return ENOMEM from ioctl.

Some callers cannot handle errors, thus __GFP_NOFAIL is used for them:
* ext4_discard_preallocations()
* ext4_mb_discard_lg_preallocations()

Fixes: adb7ef60 ("ext4: use __GFP_NOFAIL in ext4_free_blocks()")
Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 3f1d5bad

fs/ext4/mballoc.c

+14 −9
Original line number Diff line number Diff line
@@ -3887,7 +3887,8 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, 


	err = ext4_mb_load_buddy(sb, group, &e4b);

	if (err) {

		ext4_error(sb, "Error loading buddy information for %u", group);

		ext4_warning(sb, "Error %d loading buddy information for %u",

			     err, group);

		put_bh(bitmap_bh);

		return 0;

	}
@@ -4044,10 +4045,11 @@ void ext4_discard_preallocations(struct inode *inode) 
		BUG_ON(pa->pa_type != MB_INODE_PA);

		group = ext4_get_group_number(sb, pa->pa_pstart);



		err = ext4_mb_load_buddy(sb, group, &e4b);

		err = ext4_mb_load_buddy_gfp(sb, group, &e4b,

					     GFP_NOFS|__GFP_NOFAIL);

		if (err) {

			ext4_error(sb, "Error loading buddy information for %u",

					group);

			ext4_error(sb, "Error %d loading buddy information for %u",

				   err, group);

			continue;

		}
@@ -4303,11 +4305,14 @@ ext4_mb_discard_lg_preallocations(struct super_block *sb, 
	spin_unlock(&lg->lg_prealloc_lock);



	list_for_each_entry_safe(pa, tmp, &discard_list, u.pa_tmp_list) {

		int err;



		group = ext4_get_group_number(sb, pa->pa_pstart);

		if (ext4_mb_load_buddy(sb, group, &e4b)) {

			ext4_error(sb, "Error loading buddy information for %u",

					group);

		err = ext4_mb_load_buddy_gfp(sb, group, &e4b,

					     GFP_NOFS|__GFP_NOFAIL);

		if (err) {

			ext4_error(sb, "Error %d loading buddy information for %u",

				   err, group);

			continue;

		}

		ext4_lock_group(sb, group);
@@ -5127,8 +5132,8 @@ ext4_trim_all_free(struct super_block *sb, ext4_group_t group, 


	ret = ext4_mb_load_buddy(sb, group, &e4b);

	if (ret) {

		ext4_error(sb, "Error in loading buddy "

				"information for %u", group);

		ext4_warning(sb, "Error %d loading buddy information for %u",

			     ret, group);

		return ret;

	}

	bitmap = e4b.bd_bitmap;