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lockd: introduce safe async lock op

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This patch reverts mostly commit 40595cdc93 ("nfs: block notification
on fs with its own ->lock") and introduces an EXPORT_OP_ASYNC_LOCK
export flag to signal that the "own ->lock" implementation supports
async lock requests. The only main user is DLM that is used by GFS2 and
OCFS2 filesystem. Those implement their own lock() implementation and
return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93
("nfs: block notification on fs with its own ->lock") the DLM
implementation were never updated. This patch should prepare for DLM
to set the EXPORT_OP_ASYNC_LOCK export flag and update the DLM
plock implementation regarding to it.

Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Alexander Aring 2023-09-12 17:53:18 -04:00 committed by Chuck Lever
parent 1b2021bdee
commit 2dd10de8e6
4 changed files with 29 additions and 6 deletions
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7
Documentation/filesystems/nfs/exporting.rst
View File

@ -241,3 +241,10 @@ following flags are defined:
all of an inode's dirty data on last close. Exports that behave this
way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
waiting for writeback when closing such files.
EXPORT_OP_ASYNC_LOCK - Indicates a capable filesystem to do async lock
requests from lockd. Only set EXPORT_OP_ASYNC_LOCK if the filesystem has
it's own ->lock() functionality as core posix_lock_file() implementation
has no async lock request handling yet. For more information about how to
indicate an async lock request from a ->lock() file_operations struct, see
fs/locks.c and comment for the function vfs_lock_file().

4
fs/lockd/svclock.c
View File

@ -481,9 +481,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_host *host, struct nlm_lock *lock, int wait,
struct nlm_cookie *cookie, int reclaim)
{
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
struct inode *inode = nlmsvc_file_inode(file);
#endif
struct nlm_block *block = NULL;
int error;
int mode;
@ -497,7 +495,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
(long long)lock->fl.fl_end,
wait);
if (nlmsvc_file_file(file)->f_op->lock) {
if (!exportfs_lock_op_is_async(inode->i_sb->s_export_op)) {
async_block = wait;
wait = 0;
}

10
fs/nfsd/nfs4state.c
View File

@ -7487,6 +7487,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
struct nfsd4_blocked_lock *nbl = NULL;
struct file_lock *file_lock = NULL;
struct file_lock *conflock = NULL;
struct super_block *sb;
__be32 status = 0;
int lkflg;
int err;
@ -7508,6 +7509,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
dprintk("NFSD: nfsd4_lock: permission denied!\n");
return status;
}
sb = cstate->current_fh.fh_dentry->d_sb;
if (lock->lk_is_new) {
if (nfsd4_has_session(cstate))
@ -7559,7 +7561,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
fp = lock_stp->st_stid.sc_file;
switch (lock->lk_type) {
case NFS4_READW_LT:
if (nfsd4_has_session(cstate))
if (nfsd4_has_session(cstate) ||
exportfs_lock_op_is_async(sb->s_export_op))
fl_flags |= FL_SLEEP;
fallthrough;
case NFS4_READ_LT:
@ -7571,7 +7574,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
fl_type = F_RDLCK;
break;
case NFS4_WRITEW_LT:
if (nfsd4_has_session(cstate))
if (nfsd4_has_session(cstate) ||
exportfs_lock_op_is_async(sb->s_export_op))
fl_flags |= FL_SLEEP;
fallthrough;
case NFS4_WRITE_LT:
@ -7599,7 +7603,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
* for file locks), so don't attempt blocking lock notifications
* on those filesystems:
*/
if (nf->nf_file->f_op->lock)
if (!exportfs_lock_op_is_async(sb->s_export_op))
fl_flags &= ~FL_SLEEP;
nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);

14
include/linux/exportfs.h
View File

@ -224,9 +224,23 @@ struct export_operations {
atomic attribute updates
*/
#define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */
#define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */
unsigned long flags;
};
/**
* exportfs_lock_op_is_async() - export op supports async lock operation
* @export_ops: the nfs export operations to check
*
* Returns true if the nfs export_operations structure has
* EXPORT_OP_ASYNC_LOCK in their flags set
*/
static inline bool
exportfs_lock_op_is_async(const struct export_operations *export_ops)
{
return export_ops->flags & EXPORT_OP_ASYNC_LOCK;
}
extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
int *max_len, struct inode *parent,
int flags);