From 0830344c953aeabee91ac88281585756d047df39 Mon Sep 17 00:00:00 2001 From: Ojaswin Mujoo Date: Sat, 25 Mar 2023 13:43:38 +0530 Subject: [PATCH] ext4: Abstract out overlap fix/check logic in ext4_mb_normalize_request() Abstract out the logic of fixing PA overlaps in ext4_mb_normalize_request to improve readability of code. This also makes it easier to make changes to the overlap logic in future. There are no functional changes in this patch Signed-off-by: Ojaswin Mujoo Reviewed-by: Ritesh Harjani (IBM) Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/9b35f3955a1d7b66bbd713eca1e63026e01f78c1.1679731817.git.ojaswin@linux.ibm.com Signed-off-by: Theodore Ts'o --- fs/ext4/mballoc.c | 109 ++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 68 insertions(+), 41 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index db46998..e8d660f 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4002,6 +4002,73 @@ ext4_mb_pa_assert_overlap(struct ext4_allocation_context *ac, } /* + * Given an allocation context "ac" and a range "start", "end", check + * and adjust boundaries if the range overlaps with any of the existing + * preallocatoins stored in the corresponding inode of the allocation context. + * + *Parameters: + * ac allocation context + * start start of the new range + * end end of the new range + */ +static inline void +ext4_mb_pa_adjust_overlap(struct ext4_allocation_context *ac, + ext4_lblk_t *start, ext4_lblk_t *end) +{ + struct ext4_inode_info *ei = EXT4_I(ac->ac_inode); + struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); + struct ext4_prealloc_space *tmp_pa; + ext4_lblk_t new_start, new_end; + ext4_lblk_t tmp_pa_start, tmp_pa_end; + + new_start = *start; + new_end = *end; + + /* check we don't cross already preallocated blocks */ + rcu_read_lock(); + list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) { + if (tmp_pa->pa_deleted) + continue; + spin_lock(&tmp_pa->pa_lock); + if (tmp_pa->pa_deleted) { + spin_unlock(&tmp_pa->pa_lock); + continue; + } + + 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 >= tmp_pa_end || + ac->ac_o_ex.fe_logical < tmp_pa_start)); + + /* skip PAs this normalized request doesn't overlap with */ + if (tmp_pa_start >= new_end || tmp_pa_end <= new_start) { + spin_unlock(&tmp_pa->pa_lock); + continue; + } + BUG_ON(tmp_pa_start <= new_start && tmp_pa_end >= new_end); + + /* adjust start or end to be adjacent to this pa */ + if (tmp_pa_end <= ac->ac_o_ex.fe_logical) { + BUG_ON(tmp_pa_end < new_start); + new_start = tmp_pa_end; + } else if (tmp_pa_start > ac->ac_o_ex.fe_logical) { + BUG_ON(tmp_pa_start > new_end); + new_end = tmp_pa_start; + } + spin_unlock(&tmp_pa->pa_lock); + } + rcu_read_unlock(); + + /* XXX: extra loop to check we really don't overlap preallocations */ + ext4_mb_pa_assert_overlap(ac, new_start, new_end); + + *start = new_start; + *end = new_end; +} + +/* * Normalization means making request better in terms of * size and alignment */ @@ -4016,9 +4083,6 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, loff_t size, start_off; loff_t orig_size __maybe_unused; ext4_lblk_t start; - 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; /* do normalize only data requests, metadata requests do not need preallocation */ @@ -4119,47 +4183,10 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, end = start + size; - /* check we don't cross already preallocated blocks */ - rcu_read_lock(); - list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) { - if (tmp_pa->pa_deleted) - continue; - spin_lock(&tmp_pa->pa_lock); - if (tmp_pa->pa_deleted) { - spin_unlock(&tmp_pa->pa_lock); - continue; - } - - 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 >= tmp_pa_end || - ac->ac_o_ex.fe_logical < tmp_pa_start)); - - /* skip PAs this normalized request doesn't overlap with */ - if (tmp_pa_start >= end || tmp_pa_end <= start) { - spin_unlock(&tmp_pa->pa_lock); - continue; - } - BUG_ON(tmp_pa_start <= start && tmp_pa_end >= end); + ext4_mb_pa_adjust_overlap(ac, &start, &end); - /* adjust start or end to be adjacent to this pa */ - 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(&tmp_pa->pa_lock); - } - rcu_read_unlock(); size = end - start; - /* XXX: extra loop to check we really don't overlap preallocations */ - ext4_mb_pa_assert_overlap(ac, start, end); - /* * In this function "start" and "size" are normalized for better * alignment and length such that we could preallocate more blocks. -- 2.7.4