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ext4: add new attr pointer attr_mb_order

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The s_mb_best_avail_max_trim_order is of type unsigned int, and has a
range of values well beyond the normal use of the mb_order. Although the
mballoc code is careful enough that large numbers don't matter there, but
this can mislead the sysadmin into thinking that it's normal to set such
values. Hence add a new attr_id attr_mb_order with values in the range
[0, 64] to avoid storing garbage values and make us more resilient to
surprises in the future.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240319113325.3110393-6-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2024-03-19 19:33:21 +08:00 committed by Theodore Ts'o
parent 13df4d44a3
commit b7b2a5799b
1 changed files with 12 additions and 1 deletions
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13
fs/ext4/sysfs.c
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@ -30,6 +30,7 @@ typedef enum {
attr_first_error_time,
attr_last_error_time,
attr_clusters_in_group,
attr_mb_order,
attr_feature,
attr_pointer_ui,
attr_pointer_ul,
@ -210,6 +211,8 @@ EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
ext4_sb_info, s_inode_readahead_blks);
EXT4_ATTR_OFFSET(mb_group_prealloc, 0644, clusters_in_group,
ext4_sb_info, s_mb_group_prealloc);
EXT4_ATTR_OFFSET(mb_best_avail_max_trim_order, 0644, mb_order,
ext4_sb_info, s_mb_best_avail_max_trim_order);
EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
@ -225,7 +228,6 @@ EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.int
EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
EXT4_RW_ATTR_SBI_UI(mb_best_avail_max_trim_order, s_mb_best_avail_max_trim_order);
#ifdef CONFIG_EXT4_DEBUG
EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
#endif
@ -379,6 +381,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a,
switch (a->attr_id) {
case attr_inode_readahead:
case attr_clusters_in_group:
case attr_mb_order:
case attr_pointer_ui:
if (a->attr_ptr == ptr_ext4_super_block_offset)
return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr));
@ -458,6 +461,14 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a,
else
*((unsigned int *) ptr) = t;
return len;
case attr_mb_order:
ret = kstrtouint(skip_spaces(buf), 0, &t);
if (ret)
return ret;
if (t > 64)
return -EINVAL;
*((unsigned int *) ptr) = t;
return len;
case attr_clusters_in_group:
ret = kstrtouint(skip_spaces(buf), 0, &t);
if (ret)