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ext4: refactor sysfs support code
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Make the code more easily extensible as well as taking up less
compiled space.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Theodore Ts'o committed Sep 23, 2015
1 parent b579901 commit 76d33bc
Showing 1 changed file with 128 additions and 133 deletions.
261 changes: 128 additions & 133 deletions fs/ext4/sysfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,37 +15,35 @@
#include "ext4.h"
#include "ext4_jbd2.h"

typedef enum {
attr_noop,
attr_delayed_allocation_blocks,
attr_session_write_kbytes,
attr_lifetime_write_kbytes,
attr_reserved_clusters,
attr_inode_readahead,
attr_trigger_test_error,
attr_feature,
attr_pointer_ui,
attr_pointer_atomic,
} attr_id_t;

typedef enum {
ptr_explicit,
ptr_ext4_sb_info_offset,
ptr_ext4_super_block_offset,
} attr_ptr_t;

struct ext4_attr {
struct attribute attr;
ssize_t (*show)(struct ext4_attr *, struct ext4_sb_info *, char *);
ssize_t (*store)(struct ext4_attr *, struct ext4_sb_info *,
const char *, size_t);
short attr_id;
short attr_ptr;
union {
int offset;
int deprecated_val;
void *explicit_ptr;
} u;
};

static int parse_strtoull(const char *buf,
unsigned long long max, unsigned long long *value)
{
int ret;

ret = kstrtoull(skip_spaces(buf), 0, value);
if (!ret && *value > max)
ret = -EINVAL;
return ret;
}

static ssize_t delayed_allocation_blocks_show(struct ext4_attr *a,
struct ext4_sb_info *sbi,
char *buf)
{
return snprintf(buf, PAGE_SIZE, "%llu\n",
(s64) EXT4_C2B(sbi,
percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
}

static ssize_t session_write_kbytes_show(struct ext4_attr *a,
struct ext4_sb_info *sbi, char *buf)
{
Expand Down Expand Up @@ -89,58 +87,17 @@ static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
return count;
}

static ssize_t sbi_ui_show(struct ext4_attr *a,
struct ext4_sb_info *sbi, char *buf)
{
unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);

return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
}

static ssize_t sbi_ui_store(struct ext4_attr *a,
struct ext4_sb_info *sbi,
const char *buf, size_t count)
{
unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);
unsigned long t;
int ret;

ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
*ui = t;
return count;
}

static ssize_t es_ui_show(struct ext4_attr *a,
struct ext4_sb_info *sbi, char *buf)
{

unsigned int *ui = (unsigned int *) (((char *) sbi->s_es) +
a->u.offset);

return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
}

static ssize_t reserved_clusters_show(struct ext4_attr *a,
struct ext4_sb_info *sbi, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%llu\n",
(unsigned long long) atomic64_read(&sbi->s_resv_clusters));
}

static ssize_t reserved_clusters_store(struct ext4_attr *a,
struct ext4_sb_info *sbi,
const char *buf, size_t count)
{
unsigned long long val;
ext4_fsblk_t clusters = (ext4_blocks_count(sbi->s_es) >>
sbi->s_cluster_bits);
int ret;

if (parse_strtoull(buf, -1ULL, &val))
return -EINVAL;

if (val >= clusters)
ret = kstrtoull(skip_spaces(buf), 0, &val);
if (!ret || val >= clusters)
return -EINVAL;

atomic64_set(&sbi->s_resv_clusters, val);
Expand All @@ -164,70 +121,60 @@ static ssize_t trigger_test_error(struct ext4_attr *a,
return count;
}

static ssize_t sbi_deprecated_show(struct ext4_attr *a,
struct ext4_sb_info *sbi, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%d\n", a->u.deprecated_val);
#define EXT4_ATTR(_name,_mode,_id) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_##_id, \
}

#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
#define EXT4_ATTR_FUNC(_name,_mode) EXT4_ATTR(_name,_mode,_name)

#define EXT4_ATTR_FEATURE(_name) EXT4_ATTR(_name, 0444, feature)

#define EXT4_ATTR_OFFSET(_name,_mode,_id,_struct,_elname) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.show = _show, \
.store = _store, \
.attr_id = attr_##_id, \
.attr_ptr = ptr_##_struct##_offset, \
.u = { \
.offset = offsetof(struct ext4_sb_info, _elname),\
.offset = offsetof(struct _struct, _elname),\
}, \
}

#define EXT4_ATTR_OFFSET_ES(_name,_mode,_show,_store,_elname) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.show = _show, \
.store = _store, \
.u = { \
.offset = offsetof(struct ext4_super_block, _elname), \
}, \
}

#define EXT4_ATTR(name, mode, show, store) \
static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)

#define EXT4_INFO_ATTR(name) EXT4_ATTR(name, 0444, NULL, NULL)
#define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
#define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
#define EXT4_RO_ATTR_ES_UI(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)

#define EXT4_RO_ATTR_ES_UI(name, elname) \
EXT4_ATTR_OFFSET_ES(name, 0444, es_ui_show, NULL, elname)
#define EXT4_RW_ATTR_SBI_UI(name, elname) \
EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname)
#define EXT4_RW_ATTR_SBI_UI(_name,_elname) \
EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)

#define ATTR_LIST(name) &ext4_attr_##name.attr
#define EXT4_DEPRECATED_ATTR(_name, _val) \
#define EXT4_ATTR_PTR(_name,_mode,_id,_ptr) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = 0444 }, \
.show = sbi_deprecated_show, \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.attr_id = attr_##_id, \
.attr_ptr = ptr_explicit, \
.u = { \
.deprecated_val = _val, \
.explicit_ptr = _ptr, \
}, \
}

EXT4_RO_ATTR(delayed_allocation_blocks);
EXT4_RO_ATTR(session_write_kbytes);
EXT4_RO_ATTR(lifetime_write_kbytes);
EXT4_RW_ATTR(reserved_clusters);
EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
inode_readahead_blks_store, s_inode_readahead_blks);
#define ATTR_LIST(name) &ext4_attr_##name.attr

EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
EXT4_ATTR_FUNC(session_write_kbytes, 0444);
EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
EXT4_ATTR_FUNC(reserved_clusters, 0644);

EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
ext4_sb_info, s_inode_readahead_blks);
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);
EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
EXT4_DEPRECATED_ATTR(max_writeback_mb_bump, 128);
EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
EXT4_ATTR(trigger_fs_error, 0200, NULL, trigger_test_error);
EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
Expand All @@ -238,6 +185,9 @@ EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
EXT4_RO_ATTR_ES_UI(first_error_time, s_first_error_time);
EXT4_RO_ATTR_ES_UI(last_error_time, s_last_error_time);

static unsigned int old_bump_val = 128;
EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);

static struct attribute *ext4_attrs[] = {
ATTR_LIST(delayed_allocation_blocks),
ATTR_LIST(session_write_kbytes),
Expand Down Expand Up @@ -267,10 +217,10 @@ static struct attribute *ext4_attrs[] = {
};

/* Features this copy of ext4 supports */
EXT4_INFO_ATTR(lazy_itable_init);
EXT4_INFO_ATTR(batched_discard);
EXT4_INFO_ATTR(meta_bg_resize);
EXT4_INFO_ATTR(encryption);
EXT4_ATTR_FEATURE(lazy_itable_init);
EXT4_ATTR_FEATURE(batched_discard);
EXT4_ATTR_FEATURE(meta_bg_resize);
EXT4_ATTR_FEATURE(encryption);

static struct attribute *ext4_feat_attrs[] = {
ATTR_LIST(lazy_itable_init),
Expand All @@ -280,14 +230,56 @@ static struct attribute *ext4_feat_attrs[] = {
NULL,
};

static void *calc_ptr(struct ext4_attr *a, struct ext4_sb_info *sbi)
{
switch (a->attr_ptr) {
case ptr_explicit:
return a->u.explicit_ptr;
case ptr_ext4_sb_info_offset:
return (void *) (((char *) sbi) + a->u.offset);
case ptr_ext4_super_block_offset:
return (void *) (((char *) sbi->s_es) + a->u.offset);
}
return NULL;
}

static ssize_t ext4_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
s_kobj);
struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);

return a->show ? a->show(a, sbi, buf) : 0;
void *ptr = calc_ptr(a, sbi);

switch (a->attr_id) {
case attr_delayed_allocation_blocks:
return snprintf(buf, PAGE_SIZE, "%llu\n",
(s64) EXT4_C2B(sbi,
percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
case attr_session_write_kbytes:
return session_write_kbytes_show(a, sbi, buf);
case attr_lifetime_write_kbytes:
return lifetime_write_kbytes_show(a, sbi, buf);
case attr_reserved_clusters:
return snprintf(buf, PAGE_SIZE, "%llu\n",
(unsigned long long)
atomic64_read(&sbi->s_resv_clusters));
case attr_inode_readahead:
case attr_pointer_ui:
if (!ptr)
return 0;
return snprintf(buf, PAGE_SIZE, "%u\n",
*((unsigned int *) ptr));
case attr_pointer_atomic:
if (!ptr)
return 0;
return snprintf(buf, PAGE_SIZE, "%d\n",
atomic_read((atomic_t *) ptr));
case attr_feature:
return snprintf(buf, PAGE_SIZE, "supported\n");
}

return 0;
}

static ssize_t ext4_attr_store(struct kobject *kobj,
Expand All @@ -297,8 +289,27 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
s_kobj);
struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
void *ptr = calc_ptr(a, sbi);
unsigned long t;
int ret;

return a->store ? a->store(a, sbi, buf, len) : 0;
switch (a->attr_id) {
case attr_reserved_clusters:
return reserved_clusters_store(a, sbi, buf, len);
case attr_pointer_ui:
if (!ptr)
return 0;
ret = kstrtoul(skip_spaces(buf), 0, &t);
if (ret)
return ret;
*((unsigned int *) ptr) = t;
return len;
case attr_inode_readahead:
return inode_readahead_blks_store(a, sbi, buf, len);
case attr_trigger_test_error:
return trigger_test_error(a, sbi, buf, len);
}
return 0;
}

static void ext4_sb_release(struct kobject *kobj)
Expand Down Expand Up @@ -327,25 +338,9 @@ static struct kset ext4_kset = {
.kobj = {.ktype = &ext4_ktype},
};

static ssize_t ext4_feat_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
return snprintf(buf, PAGE_SIZE, "supported\n");
}

/*
* We can not use ext4_attr_show/store because it relies on the kobject
* being embedded in the ext4_sb_info structure which is definitely not
* true in this case.
*/
static const struct sysfs_ops ext4_feat_ops = {
.show = ext4_feat_show,
.store = NULL,
};

static struct kobj_type ext4_feat_ktype = {
.default_attrs = ext4_feat_attrs,
.sysfs_ops = &ext4_feat_ops,
.sysfs_ops = &ext4_attr_ops,
};

static struct kobject ext4_feat = {
Expand Down

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