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    Subject[PATCH v2 4/8] ext4: Move overlap assert logic into a separate function
    Date
    Abstract out the logic to double check for overlaps in normalize_pa to
    a separate function. Since there has been no reports in past where we
    have seen any overlaps which hits this bug_on(), in future we can
    consider calling this function under "#ifdef AGGRESSIVE_CHECK" only.

    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>
    ---
    fs/ext4/mballoc.c | 36 ++++++++++++++++++++++++------------
    1 file changed, 24 insertions(+), 12 deletions(-)

    diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
    index 89dcb72869cd..210f90a6229a 100644
    --- a/fs/ext4/mballoc.c
    +++ b/fs/ext4/mballoc.c
    @@ -3984,6 +3984,29 @@ static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
    mb_debug(sb, "goal %u blocks for locality group\n", ac->ac_g_ex.fe_len);
    }

    +static inline void
    +ext4_mb_pa_assert_overlap(struct ext4_allocation_context *ac,
    + ext4_lblk_t start, ext4_lblk_t end)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
    + struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
    + struct ext4_prealloc_space *tmp_pa;
    + ext4_lblk_t tmp_pa_start, tmp_pa_end;
    +
    + rcu_read_lock();
    + 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(&tmp_pa->pa_lock);
    + }
    + rcu_read_unlock();
    +}
    +
    /*
    * Normalization means making request better in terms of
    * size and alignment
    @@ -4140,18 +4163,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
    size = end - start;

    /* XXX: extra loop to check we really don't overlap preallocations */
    - rcu_read_lock();
    - 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(&tmp_pa->pa_lock);
    - }
    - rcu_read_unlock();
    + ext4_mb_pa_assert_overlap(ac, start, end);

    /*
    * In this function "start" and "size" are normalized for better
    --
    2.31.1
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