since path looku is being looked at, two extra nits from me:
1. some trivial jump avoidance in inode_permission()
2. but more importantly avoiding a memory access which is most likely a
cache miss when descending into devcgroup_inode_permission()
the file seems to have no maintainer fwiw
anyhow I'm confident the way forward is to add IOP_FAST_MAY_EXEC (or
similar) to elide inode_permission() in the common case to begin with.
There are quite a few branches which straight up don't need execute.
On top of that btrfs has a permission hook only to check for MAY_WRITE,
which in case of path lookup is not set. With the above flag the call
will be avoided.
Mateusz Guzik (2):
fs: touch up predicts in inode_permission()
device_cgroup: avoid access to ->i_rdev in the common case in
devcgroup_inode_permission()
fs/namei.c | 10 +++++-----
include/linux/device_cgroup.h | 7 ++++---
2 files changed, 9 insertions(+), 8 deletions(-)
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2.48.1
