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ext4: Refactor code in ext4_mb_normalize_request() and ext4_mb_use_pr…
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…eallocated()

Change some variable names to be more consistent and
refactor some of the code to make it easier to read.

There are no functional changes in this patch

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/8edcab489c06cf861b19d87207d9b0ff7ac7f3c1.1679731817.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Ojaswin Mujoo authored and Theodore Ts'o committed Apr 6, 2023
1 parent 8208972 commit bcf4349
Showing 1 changed file with 49 additions and 47 deletions.
96 changes: 49 additions & 47 deletions fs/ext4/mballoc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3994,7 +3994,8 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
loff_t orig_size __maybe_unused;
ext4_lblk_t start;
struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
struct ext4_prealloc_space *pa;
struct ext4_prealloc_space *tmp_pa;
ext4_lblk_t tmp_pa_start, tmp_pa_end;

/* do normalize only data requests, metadata requests
do not need preallocation */
Expand Down Expand Up @@ -4097,54 +4098,52 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,

/* check we don't cross already preallocated blocks */
rcu_read_lock();
list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
ext4_lblk_t pa_end;

if (pa->pa_deleted)
list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {
if (tmp_pa->pa_deleted)
continue;
spin_lock(&pa->pa_lock);
if (pa->pa_deleted) {
spin_unlock(&pa->pa_lock);
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted) {
spin_unlock(&tmp_pa->pa_lock);
continue;
}

pa_end = pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);
tmp_pa_start = tmp_pa->pa_lstart;
tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);

/* PA must not overlap original request */
BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end ||
ac->ac_o_ex.fe_logical < pa->pa_lstart));
BUG_ON(!(ac->ac_o_ex.fe_logical >= tmp_pa_end ||
ac->ac_o_ex.fe_logical < tmp_pa_start));

/* skip PAs this normalized request doesn't overlap with */
if (pa->pa_lstart >= end || pa_end <= start) {
spin_unlock(&pa->pa_lock);
if (tmp_pa_start >= end || tmp_pa_end <= start) {
spin_unlock(&tmp_pa->pa_lock);
continue;
}
BUG_ON(pa->pa_lstart <= start && pa_end >= end);
BUG_ON(tmp_pa_start <= start && tmp_pa_end >= end);

/* adjust start or end to be adjacent to this pa */
if (pa_end <= ac->ac_o_ex.fe_logical) {
BUG_ON(pa_end < start);
start = pa_end;
} else if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
BUG_ON(pa->pa_lstart > end);
end = pa->pa_lstart;
if (tmp_pa_end <= ac->ac_o_ex.fe_logical) {
BUG_ON(tmp_pa_end < start);
start = tmp_pa_end;
} else if (tmp_pa_start > ac->ac_o_ex.fe_logical) {
BUG_ON(tmp_pa_start > end);
end = tmp_pa_start;
}
spin_unlock(&pa->pa_lock);
spin_unlock(&tmp_pa->pa_lock);
}
rcu_read_unlock();
size = end - start;

/* XXX: extra loop to check we really don't overlap preallocations */
rcu_read_lock();
list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
ext4_lblk_t pa_end;

spin_lock(&pa->pa_lock);
if (pa->pa_deleted == 0) {
pa_end = pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);
BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted == 0) {
tmp_pa_start = tmp_pa->pa_lstart;
tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
BUG_ON(!(start >= tmp_pa_end || end <= tmp_pa_start));
}
spin_unlock(&pa->pa_lock);
spin_unlock(&tmp_pa->pa_lock);
}
rcu_read_unlock();

Expand Down Expand Up @@ -4359,7 +4358,8 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
int order, i;
struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
struct ext4_locality_group *lg;
struct ext4_prealloc_space *pa, *cpa = NULL;
struct ext4_prealloc_space *tmp_pa, *cpa = NULL;
ext4_lblk_t tmp_pa_start, tmp_pa_end;
ext4_fsblk_t goal_block;

/* only data can be preallocated */
Expand All @@ -4368,18 +4368,20 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)

/* first, try per-file preallocation */
rcu_read_lock();
list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {

/* all fields in this condition don't change,
* so we can skip locking for them */
if (ac->ac_o_ex.fe_logical < pa->pa_lstart ||
ac->ac_o_ex.fe_logical >= (pa->pa_lstart +
EXT4_C2B(sbi, pa->pa_len)))
tmp_pa_start = tmp_pa->pa_lstart;
tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);

if (ac->ac_o_ex.fe_logical < tmp_pa_start ||
ac->ac_o_ex.fe_logical >= tmp_pa_end)
continue;

/* non-extent files can't have physical blocks past 2^32 */
if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) &&
(pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len) >
(tmp_pa->pa_pstart + EXT4_C2B(sbi, tmp_pa->pa_len) >
EXT4_MAX_BLOCK_FILE_PHYS)) {
/*
* Since PAs don't overlap, we won't find any
Expand All @@ -4389,16 +4391,16 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
}

/* found preallocated blocks, use them */
spin_lock(&pa->pa_lock);
if (pa->pa_deleted == 0 && pa->pa_free) {
atomic_inc(&pa->pa_count);
ext4_mb_use_inode_pa(ac, pa);
spin_unlock(&pa->pa_lock);
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted == 0 && tmp_pa->pa_free) {
atomic_inc(&tmp_pa->pa_count);
ext4_mb_use_inode_pa(ac, tmp_pa);
spin_unlock(&tmp_pa->pa_lock);
ac->ac_criteria = 10;
rcu_read_unlock();
return true;
}
spin_unlock(&pa->pa_lock);
spin_unlock(&tmp_pa->pa_lock);
}
rcu_read_unlock();

Expand All @@ -4422,16 +4424,16 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
*/
for (i = order; i < PREALLOC_TB_SIZE; i++) {
rcu_read_lock();
list_for_each_entry_rcu(pa, &lg->lg_prealloc_list[i],
list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[i],
pa_inode_list) {
spin_lock(&pa->pa_lock);
if (pa->pa_deleted == 0 &&
pa->pa_free >= ac->ac_o_ex.fe_len) {
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted == 0 &&
tmp_pa->pa_free >= ac->ac_o_ex.fe_len) {

cpa = ext4_mb_check_group_pa(goal_block,
pa, cpa);
tmp_pa, cpa);
}
spin_unlock(&pa->pa_lock);
spin_unlock(&tmp_pa->pa_lock);
}
rcu_read_unlock();
}
Expand Down

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