On Wed, Aug 23, 2023 at 05:33:46PM -0400, Alexander Aring wrote:
> This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_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 40595cdc93ed
> ("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_SAFE_ASYNC_LOCK export flag and update the DLM
> plock implementation regarding to it.
>
> Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
> Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
> ---
> fs/lockd/svclock.c | 5 ++---
> fs/nfsd/nfs4state.c | 13 ++++++++++---
> include/linux/exportfs.h | 8 ++++++++
> 3 files changed, 20 insertions(+), 6 deletions(-)
I'm starting to look at these. Just so you know, it's too late for
inclusion in v6.6, but I think we can get these into shape for v6.7.
More below.
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index c43ccdf28ed9..6e3b230e8317 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -470,9 +470,7 @@ 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;
> @@ -486,7 +484,8 @@ 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 (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
> + nlmsvc_file_file(file)->f_op)) {
> async_block = wait;
> wait = 0;
> }
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 3aefbad4cc09..14ca06424ff1 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7430,6 +7430,7 @@ 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;
> @@ -7451,6 +7452,7 @@ 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))
> @@ -7502,7 +7504,9 @@ 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) ||
> + export_op_support_safe_async_lock(sb->s_export_op,
> + nf->nf_file->f_op))
> fl_flags |= FL_SLEEP;
> fallthrough;
> case NFS4_READ_LT:
> @@ -7514,7 +7518,9 @@ 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) ||
> + export_op_support_safe_async_lock(sb->s_export_op,
> + nf->nf_file->f_op))
> fl_flags |= FL_SLEEP;
> fallthrough;
> case NFS4_WRITE_LT:
> @@ -7542,7 +7548,8 @@ 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 (!export_op_support_safe_async_lock(sb->s_export_op,
> + nf->nf_file->f_op))
> fl_flags &= ~FL_SLEEP;
>
> nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
> index 11fbd0ee1370..10358a93cdc1 100644
> --- a/include/linux/exportfs.h
> +++ b/include/linux/exportfs.h
> @@ -3,6 +3,7 @@
> #define LINUX_EXPORTFS_H 1
>
> #include <linux/types.h>
> +#include <linux/fs.h>
>
> struct dentry;
> struct iattr;
> @@ -224,9 +225,16 @@ struct export_operations {
> atomic attribute updates
> */
> #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */
> +#define EXPORT_OP_SAFE_ASYNC_LOCK (0x40) /* fs can do async lock request */
We haven't been good about this recently, but the addition of new
EXPORT_OP flags need to be accompanied by updates to
Documentation/filesystems/nfs/exporting.rst.
I will see about adding documentation for other recent flags, but
please include an update to exporting.rst with this patch.
I'm not sure we need _SAFE_ in the flag name. Would
EXPORT_OP_ASYNC_LOCK be OK with you?
> unsigned long flags;
> };
>
> +static inline bool export_op_support_safe_async_lock(const struct export_operations *export_ops,
> + const struct file_operations *f_op)
> +{
> + return (export_ops->flags & EXPORT_OP_SAFE_ASYNC_LOCK) || !f_op->lock;
> +}
> +
I'd like some cosmetic changes to this API, since this seems to be
the first utility function for checking EXPORT_OP flags.
- The function name is unwieldy. How about exportfs_lock_op_is_async() ?
- Break up the long lines. It's OK with me if the return value type
is left on a different line than the function name and parameters.
- This function is globally visible, so a kdoc comment is needed.
- The f_op->lock check is common to all the call sites, but it is
not at all related to the export AFAICT. Can it be removed from
this inline function?
> extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
> int *max_len, struct inode *parent,
> int flags);
> --
> 2.31.1
>
--
Chuck Lever
