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| author | Zhang Yi <yi.zhang@huawei.com> | 2022-02-12 13:05:32 +0800 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2022-02-25 13:57:14 +0100 |
| commit | 50b3a818991074177a56c87124c7a7bdf5fa4f67 (patch) | |
| tree | 652be8cc316f75d774b70834eeb6c21073acf2e4 /fs/ext2 | |
| parent | 48b0e01109f5fb91eabb6f7c4a487b76942061cc (diff) | |
| download | linux-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.c | 6 |
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; |