nfsd: don't set a FL_LAYOUT lease for flexfiles layouts

We currently can hit a deadlock (of sorts) when trying to use flexfiles
layouts with XFS. XFS will call break_layout when something wants to
write to the file. In the case of the (super-simple) flexfiles layout
driver in knfsd, the MDS and DS are the same machine.

The client can get a layout and then issue a v3 write to do its I/O. XFS
will then call xfs_break_layouts, which will cause a CB_LAYOUTRECALL to
be issued to the client. The client however can't return the layout
until the v3 WRITE completes, but XFS won't allow the write to proceed
until the layout is returned.

Christoph says:

    XFS only cares about block-like layouts where the client has direct
    access to the file blocks.  I'd need to look how to propagate the
    flag into break_layout, but in principle we don't need to do any
    recalls on truncate ever for file and flexfile layouts.

If we're never going to recall the layout, then we don't even need to
set the lease at all. Just skip doing so on flexfiles layouts by
adding a new flag to struct nfsd4_layout_ops and skipping the lease
setting and removal when that flag is true.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/flexfilelayout.c b/fs/nfsd/flexfilelayout.c
index df880e9fa71fb60d20fe12f82ebb7ed1011ce19c..b672873830109e1d4705a4de7496a23da4227610 100644 (file)
--- a/fs/nfsd/flexfilelayout.c
+++ b/fs/nfsd/flexfilelayout.c
@@ -126,6 +126,7 @@ nfsd4_ff_proc_getdeviceinfo(struct super_block *sb, struct svc_rqst *rqstp,
 const struct nfsd4_layout_ops ff_layout_ops = {
        .notify_types           =
                        NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
+       .disable_recalls        = true,
        .proc_getdeviceinfo     = nfsd4_ff_proc_getdeviceinfo,
        .encode_getdeviceinfo   = nfsd4_ff_encode_getdeviceinfo,
        .proc_layoutget         = nfsd4_ff_proc_layoutget,

diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 2be9602b0221bd19f7492dad6266f3fd78c4e050..42aace4fc4c807ec9f41e590e777f8f8f94d7803 100644 (file)
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -174,7 +174,8 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid)
        list_del_init(&ls->ls_perfile);
        spin_unlock(&fp->fi_lock);
 
-       vfs_setlease(ls->ls_file, F_UNLCK, NULL, (void **)&ls);
+       if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
+               vfs_setlease(ls->ls_file, F_UNLCK, NULL, (void **)&ls);
        fput(ls->ls_file);
 
        if (ls->ls_recalled)
@@ -189,6 +190,9 @@ nfsd4_layout_setlease(struct nfs4_layout_stateid *ls)
        struct file_lock *fl;
        int status;
 
+       if (nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
+               return 0;
+
        fl = locks_alloc_lock();
        if (!fl)
                return -ENOMEM;

diff --git a/fs/nfsd/pnfs.h b/fs/nfsd/pnfs.h
index 0c2a716e87411d6b08258632e966666f34190b82..d27a5aa6002294eb5c3fcb6cf4db5b3e2edacd9b 100644 (file)
--- a/fs/nfsd/pnfs.h
+++ b/fs/nfsd/pnfs.h
@@ -19,6 +19,7 @@ struct nfsd4_deviceid_map {
 
 struct nfsd4_layout_ops {
        u32             notify_types;
+       bool            disable_recalls;
 
        __be32 (*proc_getdeviceinfo)(struct super_block *sb,
                        struct svc_rqst *rqstp,