ext4: fix offset overflow on 32-bit archs in ext4_iomap_begin()
ext4_iomap_begin() has a bug where offset returned in the iomap structure will be truncated to unsigned long size. On 64-bit architectures this is fine but on 32-bit architectures obviously not. Not many places actually use the offset stored in the iomap structure but one of visible failures is in SEEK_HOLE / SEEK_DATA implementation. If we create a file like: dd if=/dev/urandom of=file bs=1k seek=8m count=1 then lseek64("file", 0x100000000ULL, SEEK_DATA) wrongly returns 0x100000000 on unfixed kernel while it should return 0x200000000. Avoid the overflow by proper type cast. Fixes: 545052e9 ("ext4: Switch to iomap for SEEK_HOLE / SEEK_DATA") Signed-off-by: NJiri Slaby <jslaby@suse.cz> Signed-off-by: NJan Kara <jack@suse.cz> Signed-off-by: NTheodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org # v4.15
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