[LU-5456] ll_hsm_import() calls ll_setattr_raw() without holding i_mutex

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.7.0, Lustre 2.5.3
• Affects Version/s: Lustre 2.7.0, Lustre 2.5.3
• Labels: hsm
• Severity: 3
• Assignee: John Hammond
• Reporter: John Hammond

Description

ll_hsm_import() calls ll_setattr_raw() without holding the inode mutex but when called on a non-directory ll_setattr_raw() will unlock and relock the inode. For whatever reason a spurious unlock followed by a lock doesn't restore the balance of the universe. To see this observe that the following rm will hang in vfs_unlink() trying the lock the inode mutex:

# echo XXX > /tmp/hsm_root/f0
# lhsmtool_posix --archive=0 --hsm-root=/tmp/hsm_root/ --import f0 /mnt/lustre/f0 /mnt/lustre
lhsmtool_posix[4833]: action=1 src=f0 dst=/mnt/lustre/f0 mount_point=/mnt/lustre
lhsmtool_posix[4833]: importing '/mnt/lustre/f0' from '/tmp/hsm_root//f0'
lhsmtool_posix[4833]: imported '/mnt/lustre/f0' from '/tmp/hsm_root//0002/0000/0400/8000/0002/0000/0x280000400:0x2:0x0'=='/tmp/hsm_root//f0'
lhsmtool_posix[4833]: process finished, errs: 0 major, 0 minor, rc=0 (Success)
# rm /mnt/lustre/f0