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| author | Baokun Li <libaokun1@huawei.com> | 2022-05-28 19:00:16 +0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2022-06-18 19:35:57 -0400 |
| commit | cf4ff938b47fc5c00b0ccce53a3b50eca9b32281 (patch) | |
| tree | 8f5c001c273f043f954576f9917196398672e05b | |
| parent | a08f789d2ab5242c07e716baf9a835725046be89 (diff) | |
| download | linux-stable-cf4ff938b47fc5c00b0ccce53a3b50eca9b32281.tar.gz linux-stable-cf4ff938b47fc5c00b0ccce53a3b50eca9b32281.tar.bz2 linux-stable-cf4ff938b47fc5c00b0ccce53a3b50eca9b32281.zip | |
ext4: correct the judgment of BUG in ext4_mb_normalize_request
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@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220528110017.354175-3-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/mballoc.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 4d3740fdff90..9e06334771a3 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4185,7 +4185,22 @@ 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", |