[PATCH 0/3 v4] Fixups for l_pid

From: Benjamin Coddington
Date: Tue Jun 06 2017 - 16:45:33 EST


LTP fcntl tests (fcntl11 fcntl14 fcntl17 fcntl19 fcntl20 fcntl21) have been
failing for NFSv4 mounts due to an unexpected l_pid. What follows are some
fixups:

v2: - Rebase onto linux-next
- Revert back to using the stack in locks_mandatory_area(), and fixup
patch description for 1/3

v3: - The lkp-robot found some serious per_thread_ops performance
regressions for v1 and v2, so this version changes things around to not
acquire a reference to struct pid in fl_nspid for every lock. Instead,
it drops fl_nspid altogether, and defers the lookup of the
namespace-translated pid until it actually needed.

v4: - Instead of looking up the virtual pid by way of referencing the struct
task of the that pid, instead use find_pid_ns() and pid_nr_ns(), which
avoids a the problem where we race to get a reference to the struct task
while it may be freed.

Benjamin Coddington (3):
fs/locks: Use allocation rather than the stack in fcntl_getlk()
fs/locks: Remove fl_nspid
fs/locks: Use fs-specific l_pid for remote locks

fs/locks.c | 116 ++++++++++++++++++++++++++++++++---------------------
include/linux/fs.h | 2 +-
2 files changed, 72 insertions(+), 46 deletions(-)

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2.9.3