[PATCH RFC v5 00/29] io_uring getdents

Hao Xu
2023-08-25T13:55:58Z

This series introduce getdents64 to io_uring, the code logic is similar
with the snychronized version's. It first try nowait issue, and offload
it to io-wq threads if the first try fails.

Patch1 and Patch2 are some preparation
Patch3 supports nowait for xfs getdents code
Patch4-11 are vfs change, include adding helpers and trylock for locks
Patch12-29 supports nowait for involved xfs journal stuff
note, Patch24 and 27 are actually two questions, might be removed later.
an xfs test may come later.

Tests I've done:
a liburing test case for functional test:
https://github.com/HowHsu/liburing/commit/39dc9a8e19c06a8cebf8c2301b85320eb45c061e?diff=unified

xfstests:
test/generic: 1 fails and 171 not run
test/xfs: 72 fails and 156 not run
run the code before without this patchset, same result.
I'll try to make the environment more right to run more tests here.

Tested it with a liburing performance test:
https://github.com/HowHsu/liburing/blob/getdents/test/getdents2.c

The test is controlled by the below script[2] which runs getdents2.t 100
times and calulate the avg.
The result show that io_uring version is about 2.6% faster:

note:
[1] the number of getdents call/request in io_uring and normal sync version
are made sure to be same beforehand.

[2] run_getdents.py

```python3

import subprocess

N = 100
sum = 0.0
args = ["/data/home/howeyxu/tmpdir", "sync"]

for i in range(N):
output = subprocess.check_output(["./liburing/test/getdents2.t"] + args)
sum += float(output)

average = sum / N
print("Average of sync:", average)

sum = 0.0
args = ["/data/home/howeyxu/tmpdir", "iouring"]

for i in range(N):
output = subprocess.check_output(["./liburing/test/getdents2.t"] + args)
sum += float(output)

average = sum / N
print("Average of iouring:", average)

```

v4->v5:
- move atime update to the beginning of getdents operation
- trylock for i_rwsem
- nowait semantics for involved xfs journal stuff

v3->v4:
- add Dave's xfs nowait code and fix a deadlock problem, with some code
style tweak.
- disable fixed file to avoid a race problem for now
- add a test program.

v2->v3:
- removed the kernfs patches
- add f_pos_lock logic
- remove the "reduce last EOF getdents try" optimization since
Dominique reports that doesn't make difference
- remove the rewind logic, I think the right way is to introduce lseek
to io_uring not to patch this logic to getdents.
- add Singed-off-by of Stefan Roesch for patch 1 since checkpatch
complained that Co-developed-by someone should be accompanied with
Signed-off-by same person, I can remove them if Stefan thinks that's
not proper.

Dominique Martinet (1):
fs: split off vfs_getdents function of getdents64 syscall

Hao Xu (28):
xfs: rename XBF_TRYLOCK to XBF_NOWAIT
xfs: add NOWAIT semantics for readdir
vfs: add nowait flag for struct dir_context
vfs: add a vfs helper for io_uring file pos lock
vfs: add file_pos_unlock() for io_uring usage
vfs: add a nowait parameter for touch_atime()
vfs: add nowait parameter for file_accessed()
vfs: move file_accessed() to the beginning of iterate_dir()
vfs: add S_NOWAIT for nowait time update
vfs: trylock inode->i_rwsem in iterate_dir() to support nowait
xfs: enforce GFP_NOIO implicitly during nowait time update
xfs: make xfs_trans_alloc() support nowait semantics
xfs: support nowait for xfs_log_reserve()
xfs: don't wait for free space in xlog_grant_head_check() in nowait
case
xfs: add nowait parameter for xfs_inode_item_init()
xfs: make xfs_trans_ijoin() error out -EAGAIN
xfs: set XBF_NOWAIT for xfs_buf_read_map if necessary
xfs: support nowait memory allocation in _xfs_buf_alloc()
xfs: distinguish error type of memory allocation failure for nowait
case
xfs: return -EAGAIN when bulk memory allocation fails in nowait case
xfs: comment page allocation for nowait case in xfs_buf_find_insert()
xfs: don't print warn info for -EAGAIN error in xfs_buf_get_map()
xfs: support nowait for xfs_buf_read_map()
xfs: support nowait for xfs_buf_item_init()
xfs: return -EAGAIN when nowait meets sync in transaction commit
xfs: add a comment for xlog_kvmalloc()
xfs: support nowait semantics for xc_ctx_lock in xlog_cil_commit()
io_uring: add support for getdents

arch/s390/hypfs/inode.c | 2 +-
block/fops.c | 2 +-
fs/btrfs/file.c | 2 +-
fs/btrfs/inode.c | 2 +-
fs/cachefiles/namei.c | 2 +-
fs/coda/dir.c | 4 +--
fs/ecryptfs/file.c | 4 +--
fs/ext2/file.c | 4 +--
fs/ext4/file.c | 6 ++--
fs/f2fs/file.c | 4 +--
fs/file.c | 13 +++++++
fs/fuse/dax.c | 2 +-
fs/fuse/file.c | 4 +--
fs/gfs2/file.c | 2 +-
fs/hugetlbfs/inode.c | 2 +-
fs/inode.c | 10 +++---
fs/internal.h | 8 +++++
fs/namei.c | 4 +--
fs/nfsd/vfs.c | 2 +-
fs/nilfs2/file.c | 2 +-
fs/orangefs/file.c | 2 +-
fs/orangefs/inode.c | 2 +-
fs/overlayfs/file.c | 2 +-
fs/overlayfs/inode.c | 2 +-
fs/pipe.c | 2 +-
fs/ramfs/file-nommu.c | 2 +-
fs/readdir.c | 61 +++++++++++++++++++++++++--------
fs/smb/client/cifsfs.c | 2 +-
fs/splice.c | 2 +-
fs/stat.c | 2 +-
fs/ubifs/file.c | 2 +-
fs/udf/file.c | 2 +-
fs/xfs/libxfs/xfs_alloc.c | 2 +-
fs/xfs/libxfs/xfs_attr_remote.c | 2 +-
fs/xfs/libxfs/xfs_btree.c | 2 +-
fs/xfs/libxfs/xfs_da_btree.c | 16 +++++++++
fs/xfs/libxfs/xfs_da_btree.h | 1 +
fs/xfs/libxfs/xfs_dir2_block.c | 7 ++--
fs/xfs/libxfs/xfs_dir2_priv.h | 2 +-
fs/xfs/libxfs/xfs_shared.h | 2 ++
fs/xfs/libxfs/xfs_trans_inode.c | 12 +++++--
fs/xfs/scrub/dir.c | 2 +-
fs/xfs/scrub/readdir.c | 2 +-
fs/xfs/scrub/repair.c | 2 +-
fs/xfs/xfs_buf.c | 43 +++++++++++++++++------
fs/xfs/xfs_buf.h | 4 +--
fs/xfs/xfs_buf_item.c | 9 +++--
fs/xfs/xfs_buf_item.h | 2 +-
fs/xfs/xfs_buf_item_recover.c | 2 +-
fs/xfs/xfs_dir2_readdir.c | 49 ++++++++++++++++++++------
fs/xfs/xfs_dquot.c | 2 +-
fs/xfs/xfs_file.c | 6 ++--
fs/xfs/xfs_inode.c | 27 +++++++++++++++
fs/xfs/xfs_inode.h | 17 +++++----
fs/xfs/xfs_inode_item.c | 12 ++++---
fs/xfs/xfs_inode_item.h | 3 +-
fs/xfs/xfs_iops.c | 31 ++++++++++++++---
fs/xfs/xfs_log.c | 33 ++++++++++++------
fs/xfs/xfs_log.h | 5 +--
fs/xfs/xfs_log_cil.c | 17 +++++++--
fs/xfs/xfs_log_priv.h | 4 +--
fs/xfs/xfs_trans.c | 44 ++++++++++++++++++++----
fs/xfs/xfs_trans.h | 2 +-
fs/xfs/xfs_trans_buf.c | 18 ++++++++--
fs/zonefs/file.c | 4 +--
include/linux/file.h | 7 ++++
include/linux/fs.h | 16 +++++++--
include/uapi/linux/io_uring.h | 1 +
io_uring/fs.c | 53 ++++++++++++++++++++++++++++
io_uring/fs.h | 3 ++
io_uring/opdef.c | 8 +++++
kernel/bpf/inode.c | 4 +--
mm/filemap.c | 8 ++---
mm/shmem.c | 6 ++--
net/unix/af_unix.c | 4 +--
75 files changed, 499 insertions(+), 161 deletions(-)

--
2.25.1