[PATCH 10/29] vfs: add S_NOWAIT for nowait time update

Hao Xu
2023-08-25T14:00:19Z

Add a new time flag S_NOWAIT to support nowait time update. Deliver it
to specific filesystem and error out -EAGAIN when it would block.

Signed-off-by: Hao Xu <howeyxu@tencent.com>
---
fs/inode.c | 9 +++++----
fs/xfs/xfs_iops.c | 8 +++++++-
include/linux/fs.h | 1 +
3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index e83b836f2d09..eb3db34a3e6e 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1966,12 +1966,13 @@ int touch_atime(const struct path *path, bool nowait)
struct vfsmount *mnt = path->mnt;
struct inode *inode = d_inode(path->dentry);
struct timespec64 now;
+ int ret = 0;

if (!atime_needs_update(path, inode))
- return 0;
+ return ret;

if (!sb_start_write_trylock(inode->i_sb))
- return 0;
+ return ret;

if (__mnt_want_write(mnt) != 0)
goto skip_update;
@@ -1985,11 +1986,11 @@ int touch_atime(const struct path *path, bool nowait)
* of the fs read only, e.g. subvolumes in Btrfs.
*/
now = current_time(inode);
- inode_update_time(inode, &now, S_ATIME);
+ ret = inode_update_time(inode, &now, S_ATIME | (nowait ? S_NOWAIT : 0));
__mnt_drop_write(mnt);
skip_update:
sb_end_write(inode->i_sb);
- return 0;
+ return ret;
}
EXPORT_SYMBOL(touch_atime);

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 24718adb3c16..bf1d4c31f009 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1053,7 +1053,13 @@ xfs_vn_update_time(
if (error)
return error;

- xfs_ilock(ip, XFS_ILOCK_EXCL);
+ if (flags & S_NOWAIT) {
+ if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+ return -EAGAIN;
+ } else {
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ }
+
if (flags & S_CTIME)
inode->i_ctime = *now;
if (flags & S_MTIME)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ed60b3d70d1e..f8c267ee5cb7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2198,6 +2198,7 @@ enum file_time_flags {
S_MTIME = 2,
S_CTIME = 4,
S_VERSION = 8,
+ S_NOWAIT = 16,
};

extern bool atime_needs_update(const struct path *, struct inode *);
--
2.25.1