From 0d606e2c9fccdd4e67febf1e2da500e1bfe9e045 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 23 Apr 2013 08:59:35 -0400 Subject: [PATCH] ext4: fix type-widening bug in inode table readahead code Due to a missing cast, the high 32-bits of a 64-bit block number used when calculating the readahead block for inode tables can get lost. This means we can end up fetching the wrong blocks for readahead for file systems > 16TB. Linus found this when experimenting with an enhacement to the sparse static code checker which checks for missing widening casts before binary "not" operators. Reported-by: Linus Torvalds Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d7518e2728f1..793d44b84d7f 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4011,13 +4011,14 @@ make_io: if (EXT4_SB(sb)->s_inode_readahead_blks) { ext4_fsblk_t b, end, table; unsigned num; + __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks; table = ext4_inode_table(sb, gdp); /* s_inode_readahead_blks is always a power of 2 */ - b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1); + b = block & ~((ext4_fsblk_t) ra_blks - 1); if (table > b) b = table; - end = b + EXT4_SB(sb)->s_inode_readahead_blks; + end = b + ra_blks; num = EXT4_INODES_PER_GROUP(sb); if (ext4_has_group_desc_csum(sb)) num -= ext4_itable_unused_count(sb, gdp); -- 2.30.2