3.16.70-rc1 review patch. If anyone has any objections, please let me know.
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From: Jan Kara jack@suse.cz
commit 1c2d14212b15a60300a2d4f6364753e87394c521 upstream.
When ext2 filesystem is created with 64k block size, ext2_max_size() will return value less than 0. Also, we cannot write any file in this fs since the sb->maxbytes is less than 0. The core of the problem is that the size of block index tree for such large block size is more than i_blocks can carry. So fix the computation to count with this possibility.
File size limits computed with the new function for the full range of possible block sizes look like:
bits file_size 10 17247252480 11 275415851008 12 2196873666560 13 2197948973056 14 2198486220800 15 2198754754560 16 2198888906752
Reported-by: yangerkun yangerkun@huawei.com Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/ext2/super.c | 39 +++++++++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 14 deletions(-)
--- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -701,7 +701,8 @@ static loff_t ext2_max_size(int bits) { loff_t res = EXT2_NDIR_BLOCKS; int meta_blocks; - loff_t upper_limit; + unsigned int upper_limit; + unsigned int ppb = 1 << (bits-2);
/* This is calculated to be the largest file size for a * dense, file such that the total number of @@ -715,24 +716,34 @@ static loff_t ext2_max_size(int bits) /* total blocks in file system block size */ upper_limit >>= (bits - 9);
- - /* indirect blocks */ - meta_blocks = 1; - /* double indirect blocks */ - meta_blocks += 1 + (1LL << (bits-2)); - /* tripple indirect blocks */ - meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2))); - - upper_limit -= meta_blocks; - upper_limit <<= bits; - + /* Compute how many blocks we can address by block tree */ res += 1LL << (bits-2); res += 1LL << (2*(bits-2)); res += 1LL << (3*(bits-2)); + /* Does block tree limit file size? */ + if (res < upper_limit) + goto check_lfs; + + res = upper_limit; + /* How many metadata blocks are needed for addressing upper_limit? */ + upper_limit -= EXT2_NDIR_BLOCKS; + /* indirect blocks */ + meta_blocks = 1; + upper_limit -= ppb; + /* double indirect blocks */ + if (upper_limit < ppb * ppb) { + meta_blocks += 1 + DIV_ROUND_UP(upper_limit, ppb); + res -= meta_blocks; + goto check_lfs; + } + meta_blocks += 1 + ppb; + upper_limit -= ppb * ppb; + /* tripple indirect blocks for the rest */ + meta_blocks += 1 + DIV_ROUND_UP(upper_limit, ppb) + + DIV_ROUND_UP(upper_limit, ppb*ppb); + res -= meta_blocks; +check_lfs: res <<= bits; - if (res > upper_limit) - res = upper_limit; - if (res > MAX_LFS_FILESIZE) res = MAX_LFS_FILESIZE;