This prepares for future changes, where the layout state needs
to change atomically with several other variables. In particular,
it will need to know if lo->segs is empty, as we test that instead
of manipulating the NFS_LAYOUT_STATEID_SET bit. Moreover, the
layoutstateid is not really a read-mostly structure, as it is
written almost as often as it is read.
The behavior of pnfs_get_layout_stateid is also slightly changed, so that
it no longer changes the stateid. Its name is changed to +pnfs_choose_layoutget_stateid.
Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
---
fs/nfs/nfs4xdr.c | 2 +-
fs/nfs/pnfs.c | 79 +++++++++++++++--------------------------------------
fs/nfs/pnfs.h | 7 ++---
3 files changed, 27 insertions(+), 61 deletions(-)
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index f3f9915..4e28242 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1798,7 +1798,7 @@ encode_layoutget(struct xdr_stream *xdr,
p = xdr_encode_hyper(p, args->range.offset);
p = xdr_encode_hyper(p, args->range.length);
p = xdr_encode_hyper(p, args->minlength);
- pnfs_get_layout_stateid(&stateid, NFS_I(args->inode)->layout,
+ pnfs_choose_layoutget_stateid(&stateid, NFS_I(args->inode)->layout,
args->ctx->state);
p = xdr_encode_opaque_fixed(p, &stateid.data, NFS4_STATEID_SIZE);
*p = cpu_to_be32(args->maxcount);
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 6736f9e..08313f53 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -258,9 +258,6 @@ pnfs_clear_lseg_list(struct pnfs_layout_hdr *lo, struct list_head *tmp_list)
/* List does not take a reference, so no need for put here */
list_del_init(&lo->plh_layouts);
spin_unlock(&clp->cl_lock);
- write_seqlock(&lo->plh_seqlock);
- clear_bit(NFS_LAYOUT_STATEID_SET, &lo->plh_flags);
- write_sequnlock(&lo->plh_seqlock);
dprintk("%s:Return\n", __func__);
}
@@ -319,69 +316,40 @@ pnfs_destroy_all_layouts(struct nfs_client *clp)
}
}
-/* update lo->plh_stateid with new if is more recent
- *
- * lo->plh_stateid could be the open stateid, in which case we just use what given.
- */
+/* update lo->plh_stateid with new if is more recent */
static void
pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo,
const nfs4_stateid *new)
{
- nfs4_stateid *old = &lo->plh_stateid;
- bool overwrite = false;
-
- write_seqlock(&lo->plh_seqlock);
- if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->plh_flags) ||
- memcmp(old->stateid.other, new->stateid.other, sizeof(new->stateid.other)))
- overwrite = true;
- else {
- u32 oldseq, newseq;
-
- oldseq = be32_to_cpu(old->stateid.seqid);
- newseq = be32_to_cpu(new->stateid.seqid);
- if ((int)(newseq - oldseq) > 0)
- overwrite = true;
- }
- if (overwrite)
- memcpy(&old->stateid, &new->stateid, sizeof(new->stateid));
- write_sequnlock(&lo->plh_seqlock);
-}
-
-static void
-pnfs_layout_from_open_stateid(struct pnfs_layout_hdr *lo,
- struct nfs4_state *state)
-{
- int seq;
+ u32 oldseq, newseq;
- dprintk("--> %s\n", __func__);
- write_seqlock(&lo->plh_seqlock);
- do {
- seq = read_seqbegin(&state->seqlock);
- memcpy(lo->plh_stateid.data, state->stateid.data,
- sizeof(state->stateid.data));
- } while (read_seqretry(&state->seqlock, seq));
- set_bit(NFS_LAYOUT_STATEID_SET, &lo->plh_flags);
- write_sequnlock(&lo->plh_seqlock);
- dprintk("<-- %s\n", __func__);
+ oldseq = be32_to_cpu(lo->plh_stateid.stateid.seqid);
+ newseq = be32_to_cpu(new->stateid.seqid);
+ if ((int)(newseq - oldseq) > 0)
+ memcpy(&lo->plh_stateid, &new->stateid, sizeof(new->stateid));
}
-void
-pnfs_get_layout_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
- struct nfs4_state *open_state)
+int
+pnfs_choose_layoutget_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
+ struct nfs4_state *open_state)
{
- int seq;
+ int status = 0;
dprintk("--> %s\n", __func__);
- do {
- seq = read_seqbegin(&lo->plh_seqlock);
- if (!test_bit(NFS_LAYOUT_STATEID_SET, &lo->plh_flags)) {
- /* This will trigger retry of the read */
- pnfs_layout_from_open_stateid(lo, open_state);
- } else
- memcpy(dst->data, lo->plh_stateid.data,
- sizeof(lo->plh_stateid.data));
- } while (read_seqretry(&lo->plh_seqlock, seq));
+ spin_lock(&lo->plh_inode->i_lock);
+ if (list_empty(&lo->plh_segs)) {
+ int seq;
+
+ do {
+ seq = read_seqbegin(&open_state->seqlock);
+ memcpy(dst->data, open_state->stateid.data,
+ sizeof(open_state->stateid.data));
+ } while (read_seqretry(&open_state->seqlock, seq));
+ } else
+ memcpy(dst->data, lo->plh_stateid.data, sizeof(lo->plh_stateid.data));
+ spin_unlock(&lo->plh_inode->i_lock);
dprintk("<-- %s\n", __func__);
+ return status;
}
/*
@@ -496,7 +464,6 @@ alloc_init_layout_hdr(struct inode *ino)
lo->plh_refcount = 1;
INIT_LIST_HEAD(&lo->plh_layouts);
INIT_LIST_HEAD(&lo->plh_segs);
- seqlock_init(&lo->plh_seqlock);
lo->plh_inode = ino;
return lo;
}
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index c2f1086..1093720 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -44,7 +44,6 @@ struct pnfs_layout_segment {
enum {
NFS_LAYOUT_RO_FAILED = 0, /* get ro layout failed stop trying */
NFS_LAYOUT_RW_FAILED, /* get rw layout failed stop trying */
- NFS_LAYOUT_STATEID_SET, /* have a valid layout stateid */
};
/* Per-layout driver specific registration structure */
@@ -63,7 +62,6 @@ struct pnfs_layout_hdr {
unsigned long plh_refcount;
struct list_head plh_layouts; /* other client layouts */
struct list_head plh_segs; /* layout segments list */
- seqlock_t plh_seqlock; /* Protects the stateid */
nfs4_stateid plh_stateid;
unsigned long plh_flags;
struct inode *plh_inode;
@@ -143,8 +141,9 @@ int pnfs_layout_process(struct nfs4_layoutget *lgp);
void pnfs_destroy_layout(struct nfs_inode *);
void pnfs_destroy_all_layouts(struct nfs_client *);
void put_layout_hdr(struct inode *inode);
-void pnfs_get_layout_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
- struct nfs4_state *open_state);
+int pnfs_choose_layoutget_stateid(nfs4_stateid *dst,
+ struct pnfs_layout_hdr *lo,
+ struct nfs4_state *open_state);
static inline int lo_fail_bit(u32 iomode)
--
1.7.2.1
--
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