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authorZhang Yi <yi.zhang@huawei.com>2022-02-12 13:05:32 +0800
committerJan Kara <jack@suse.cz>2022-02-25 13:57:14 +0100
commit50b3a818991074177a56c87124c7a7bdf5fa4f67 (patch)
tree652be8cc316f75d774b70834eeb6c21073acf2e4 /fs/ext2
parent48b0e01109f5fb91eabb6f7c4a487b76942061cc (diff)
downloadlinux-50b3a818991074177a56c87124c7a7bdf5fa4f67.tar.bz2
ext2: correct max file size computing
We need to calculate the max file size accurately if the total blocks that can address by block tree exceed the upper_limit. But this check is not correct now, it only compute the total data blocks but missing metadata blocks are needed. So in the case of "data blocks < upper_limit && total blocks > upper_limit", we will get wrong result. Fortunately, this case could not happen in reality, but it's confused and better to correct the computing. bits data blocks metadatablocks upper_limit 10 16843020 66051 2147483647 11 134480396 263171 1073741823 12 1074791436 1050627 536870911 (*) 13 8594130956 4198403 268435455 (*) 14 68736258060 16785411 134217727 (*) 15 549822930956 67125251 67108863 (*) 16 4398314962956 268468227 33554431 (*) [*] Need to calculate in depth. Fixes: 1c2d14212b15 ("ext2: Fix underflow in ext2_max_size()") Link: https://lore.kernel.org/r/20220212050532.179055-1-yi.zhang@huawei.com Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/ext2')
-rw-r--r--fs/ext2/super.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 94f1fbd7d3ac..6d4f5ef74766 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -753,8 +753,12 @@ static loff_t ext2_max_size(int bits)
res += 1LL << (bits-2);
res += 1LL << (2*(bits-2));
res += 1LL << (3*(bits-2));
+ /* Compute how many metadata blocks are needed */
+ meta_blocks = 1;
+ meta_blocks += 1 + ppb;
+ meta_blocks += 1 + ppb + ppb * ppb;
/* Does block tree limit file size? */
- if (res < upper_limit)
+ if (res + meta_blocks <= upper_limit)
goto check_lfs;
res = upper_limit;