From: Baokun Li <libaokun1@xxxxxxxxxx> [ Upstream commit cf4ff938b47fc5c00b0ccce53a3b50eca9b32281 ] ext4_mb_normalize_request() can move logical start of allocated blocks to reduce fragmentation and better utilize preallocation. However logical block requested as a start of allocation (ac->ac_o_ex.fe_logical) should always be covered by allocated blocks so we should check that by modifying and to or in the assertion. Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Ritesh Harjani <ritesh.list@xxxxxxxxx> Link: https://lore.kernel.org/r/20220528110017.354175-3-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/ext4/mballoc.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index db8243627b08..0f7cbb59419b 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3242,7 +3242,22 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, } rcu_read_unlock(); - if (start + size <= ac->ac_o_ex.fe_logical && + /* + * In this function "start" and "size" are normalized for better + * alignment and length such that we could preallocate more blocks. + * This normalization is done such that original request of + * ac->ac_o_ex.fe_logical & fe_len should always lie within "start" and + * "size" boundaries. + * (Note fe_len can be relaxed since FS block allocation API does not + * provide gurantee on number of contiguous blocks allocation since that + * depends upon free space left, etc). + * In case of inode pa, later we use the allocated blocks + * [pa_start + fe_logical - pa_lstart, fe_len/size] from the preallocated + * range of goal/best blocks [start, size] to put it at the + * ac_o_ex.fe_logical extent of this inode. + * (See ext4_mb_use_inode_pa() for more details) + */ + if (start + size <= ac->ac_o_ex.fe_logical || start > ac->ac_o_ex.fe_logical) { ext4_msg(ac->ac_sb, KERN_ERR, "start %lu, size %lu, fe_logical %lu", -- 2.35.1
