[PATCH v2 0/4] io_uring: call statx directly

[Bijan Mottahedeh <bijan.mottahedeh@oracle.com>]

v1 -> v2

- Separate statx and open in io_kiocb 
- Remove external declarations for unused statx interfaces

This patch set is a fix for the liburing statx test failure.

The test fails with a "Miscompare between io_uring and statx" error
because the statx system call path has additional processing in vfs_statx():

        stat->result_mask |= STATX_MNT_ID;
        if (path.mnt->mnt_root == path.dentry)
                stat->attributes |= STATX_ATTR_MOUNT_ROOT;
        stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;

which then results in different result_mask values.

Allowing the system call to be invoked directly simplifies the io_uring
interface and avoids potential future incompatibilities.  I'm not sure
if there was other reasoning fort not doing so initially.

One issue I cannot account for is the difference in "used" memory reported
by free(1) after running the statx a large (10000) number of times.

The difference is significant ~100k and doesn't really change after
dropping caches.

I enabled memory leak detection and couldn't see anything related to the test.

Bijan Mottahedeh (4):
  io_uring: add io_statx structure
  statx: allow system call to be invoked from io_uring
  io_uring: call statx directly
  statx: hide interfaces no longer used by io_uring

 fs/internal.h |  4 ++--
 fs/io_uring.c | 72 +++++++++++++++--------------------------------------------
 fs/stat.c     | 37 +++++++++++++++++-------------
 3 files changed, 42 insertions(+), 71 deletions(-)

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1.8.3.1