With the ext3/ext4 directory index implementation hashes are used to specify offsets for llseek(). For compatibility with NFSv2 and 32-bit user space on 64-bit systems (kernel space) ext3/ext4 currently only return 32-bit hashes and therefore the probability of hash collisions for larger directories is rather high. As recently reported on the NFS mailing list that theoretical problem also happens on real systems: http://comments.gmane.org/gmane.linux.nfs/40863 The following series adds two new open flags to tell ext4 to to 32-bit or 64-bit hash values for llseek() calls. These flags are then used by NFS to use 32-bit (NFSv2) or 64-bit offsets (hashes in case of ext3/ext4) for readdir and seekdir. User space does not need to specify these flags, but usually the check for is_32bit_api() should be sufficient. --- Bernd Schubert (2): Remove check for a 32-bit cookie in nfsd4_readdir() nfsd: vfs_llseek() with O_32BITHASH or O_64BITHASH Fan Yong (1): Return 32/64-bit dir name hash according to usage type fs/ext4/dir.c | 160 ++++++++++++++++++++++++++++++++++--------- fs/fcntl.c | 5 + fs/nfsd/nfs4proc.c | 2 - fs/nfsd/vfs.c | 6 ++ include/asm-generic/fcntl.h | 9 ++ 5 files changed, 145 insertions(+), 37 deletions(-) -- Bernd Schubert -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
