nfsd: implement pNFS layout recalls
Add support to issue layout recalls to clients. For now we only support
full-file recalls to get a simple and stable implementation. This allows
to embedd a nfsd4_callback structure in the layout_state and thus avoid
any memory allocations under spinlocks during a recall. For normal
use cases that do not intent to share a single file between multiple
clients this implementation is fully sufficient.
To ensure layouts are recalled on local filesystem access each layout
state registers a new FL_LAYOUT lease with the kernel file locking code,
which filesystems that support pNFS exports that require recalls need
to break on conflicting access patterns.
The XDR code is based on the old pNFS server implementation by
Andy Adamson, Benny Halevy, Boaz Harrosh, Dean Hildebrand, Fred Isaman,
Marc Eshel, Mike Sager and Ricardo Labiaga.
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 5f66b7f..4f3bfeb 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -502,6 +502,7 @@
bool fi_had_conflict;
#ifdef CONFIG_NFSD_PNFS
struct list_head fi_lo_states;
+ atomic_t fi_lo_recalls;
#endif
};
@@ -542,6 +543,10 @@
spinlock_t ls_lock;
struct list_head ls_layouts;
u32 ls_layout_type;
+ struct file *ls_file;
+ struct nfsd4_callback ls_recall;
+ stateid_t ls_recall_sid;
+ bool ls_recalled;
};
static inline struct nfs4_layout_stateid *layoutstateid(struct nfs4_stid *s)
@@ -556,6 +561,7 @@
enum nfsd4_cb_op {
NFSPROC4_CLNT_CB_NULL = 0,
NFSPROC4_CLNT_CB_RECALL,
+ NFSPROC4_CLNT_CB_LAYOUT,
NFSPROC4_CLNT_CB_SEQUENCE,
};