NFS: Implement SEEK

The SEEK operation is used when an application makes an lseek call with
either the SEEK_HOLE or SEEK_DATA flags set.  I fall back on
nfs_file_llseek() if the server does not have SEEK support.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

9 files changed, 221 insertions, 2 deletions

diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index 4782e0840dcc..04cb830fa09f 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -28,6 +28,7 @@ nfsv4-y := nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o nfs4super.o nfs4file.o
 nfsv4-$(CONFIG_NFS_USE_LEGACY_DNS) += cache_lib.o
 nfsv4-$(CONFIG_SYSCTL)  += nfs4sysctl.o
 nfsv4-$(CONFIG_NFS_V4_1)        += pnfs.o pnfs_dev.o
+nfsv4-$(CONFIG_NFS_V4_2)        += nfs42proc.o
 
 obj-$(CONFIG_PNFS_FILE_LAYOUT) += filelayout/
 obj-$(CONFIG_PNFS_OBJLAYOUT) += objlayout/
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 577a36f0a510..56d073ede3c7 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -716,6 +716,7 @@ struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
         kfree(new);
         return res;
 }
+EXPORT_SYMBOL_GPL(nfs_get_lock_context);
 
 void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
 {
@@ -728,6 +729,7 @@ void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
         spin_unlock(&inode->i_lock);
         kfree(l_ctx);
 }
+EXPORT_SYMBOL_GPL(nfs_put_lock_context);
 
 /**
  * nfs_close_context - Common close_context() routine NFSv2/v3
diff --git a/fs/nfs/nfs42.h b/fs/nfs/nfs42.h
new file mode 100644
index 000000000000..d10333a197bf
--- /dev/null
+++ b/fs/nfs/nfs42.h
@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2014 Anna Schumaker <Anna.Schumaker@Netapp.com>
+ */
+
+#ifndef __LINUX_FS_NFS_NFS4_2_H
+#define __LINUX_FS_NFS_NFS4_2_H
+
+/* nfs4.2proc.c */
+loff_t nfs42_proc_llseek(struct file *, loff_t, int);
+
+/* nfs4.2xdr.h */
+extern struct rpc_procinfo nfs4_2_procedures[];
+
+#endif /* __LINUX_FS_NFS_NFS4_2_H */
diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
new file mode 100644
index 000000000000..0886f1db5917
--- /dev/null
+++ b/fs/nfs/nfs42proc.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2014 Anna Schumaker <Anna.Schumaker@Netapp.com>
+ */
+#include <linux/fs.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/nfs.h>
+#include <linux/nfs3.h>
+#include <linux/nfs4.h>
+#include <linux/nfs_xdr.h>
+#include <linux/nfs_fs.h>
+#include "nfs4_fs.h"
+#include "nfs42.h"
+
+static int nfs42_set_rw_stateid(nfs4_stateid *dst, struct file *file,
+                                fmode_t fmode)
+{
+        struct nfs_open_context *open;
+        struct nfs_lock_context *lock;
+        int ret;
+
+        open = get_nfs_open_context(nfs_file_open_context(file));
+        lock = nfs_get_lock_context(open);
+        if (IS_ERR(lock)) {
+                put_nfs_open_context(open);
+                return PTR_ERR(lock);
+        }
+
+        ret = nfs4_set_rw_stateid(dst, open, lock, fmode);
+
+        nfs_put_lock_context(lock);
+        put_nfs_open_context(open);
+        return ret;
+}
+
+loff_t nfs42_proc_llseek(struct file *filep, loff_t offset, int whence)
+{
+        struct inode *inode = file_inode(filep);
+        struct nfs42_seek_args args = {
+                .sa_fh          = NFS_FH(inode),
+                .sa_offset      = offset,
+                .sa_what        = (whence == SEEK_HOLE) ?
+                                        NFS4_CONTENT_HOLE : NFS4_CONTENT_DATA,
+        };
+        struct nfs42_seek_res res;
+        struct rpc_message msg = {
+                .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SEEK],
+                .rpc_argp = &args,
+                .rpc_resp = &res,
+        };
+        struct nfs_server *server = NFS_SERVER(inode);
+        int status;
+
+        if (!(server->caps & NFS_CAP_SEEK))
+                return -ENOTSUPP;
+
+        status = nfs42_set_rw_stateid(&args.sa_stateid, filep, FMODE_READ);
+        if (status)
+                return status;
+
+        nfs_wb_all(inode);
+        status = nfs4_call_sync(server->client, server, &msg,
+                                &args.seq_args, &res.seq_res, 0);
+        if (status == -ENOTSUPP)
+                server->caps &= ~NFS_CAP_SEEK;
+        if (status)
+                return status;
+
+        return vfs_setpos(filep, res.sr_offset, inode->i_sb->s_maxbytes);
+}
diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c
new file mode 100644
index 000000000000..c90469b604b8
--- /dev/null
+++ b/fs/nfs/nfs42xdr.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2014 Anna Schumaker <Anna.Schumaker@Netapp.com>
+ */
+#ifndef __LINUX_FS_NFS_NFS4_2XDR_H
+#define __LINUX_FS_NFS_NFS4_2XDR_H
+
+#define encode_seek_maxsz               (op_encode_hdr_maxsz + \
+                                         encode_stateid_maxsz + \
+                                         2 /* offset */ + \
+                                         1 /* whence */)
+#define decode_seek_maxsz               (op_decode_hdr_maxsz + \
+                                         1 /* eof */ + \
+                                         1 /* whence */ + \
+                                         2 /* offset */ + \
+                                         2 /* length */)
+
+#define NFS4_enc_seek_sz                (compound_encode_hdr_maxsz + \
+                                         encode_putfh_maxsz + \
+                                         encode_seek_maxsz)
+#define NFS4_dec_seek_sz                (compound_decode_hdr_maxsz + \
+                                         decode_putfh_maxsz + \
+                                         decode_seek_maxsz)
+
+
+static void encode_seek(struct xdr_stream *xdr,
+                        struct nfs42_seek_args *args,
+                        struct compound_hdr *hdr)
+{
+        encode_op_hdr(xdr, OP_SEEK, decode_seek_maxsz, hdr);
+        encode_nfs4_stateid(xdr, &args->sa_stateid);
+        encode_uint64(xdr, args->sa_offset);
+        encode_uint32(xdr, args->sa_what);
+}
+
+/*
+ * Encode SEEK request
+ */
+static void nfs4_xdr_enc_seek(struct rpc_rqst *req,
+                              struct xdr_stream *xdr,
+                              struct nfs42_seek_args *args)
+{
+        struct compound_hdr hdr = {
+                .minorversion = nfs4_xdr_minorversion(&args->seq_args),
+        };
+
+        encode_compound_hdr(xdr, req, &hdr);
+        encode_sequence(xdr, &args->seq_args, &hdr);
+        encode_putfh(xdr, args->sa_fh, &hdr);
+        encode_seek(xdr, args, &hdr);
+        encode_nops(&hdr);
+}
+
+static int decode_seek(struct xdr_stream *xdr, struct nfs42_seek_res *res)
+{
+        int status;
+        __be32 *p;
+
+        status = decode_op_hdr(xdr, OP_SEEK);
+        if (status)
+                return status;
+
+        p = xdr_inline_decode(xdr, 4 + 8);
+        if (unlikely(!p))
+                goto out_overflow;
+
+        res->sr_eof = be32_to_cpup(p++);
+        p = xdr_decode_hyper(p, &res->sr_offset);
+        return 0;
+
+out_overflow:
+        print_overflow_msg(__func__, xdr);
+        return -EIO;
+}
+
+/*
+ * Decode SEEK request
+ */
+static int nfs4_xdr_dec_seek(struct rpc_rqst *rqstp,
+                             struct xdr_stream *xdr,
+                             struct nfs42_seek_res *res)
+{
+        struct compound_hdr hdr;
+        int status;
+
+        status = decode_compound_hdr(xdr, &hdr);
+        if (status)
+                goto out;
+        status = decode_sequence(xdr, &res->seq_res, rqstp);
+        if (status)
+                goto out;
+        status = decode_putfh(xdr);
+        if (status)
+                goto out;
+        status = decode_seek(xdr, res);
+out:
+        return status;
+}
+#endif /* __LINUX_FS_NFS_NFS4_2XDR_H */
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 92193eddb41d..b6b518d18aa7 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -227,6 +227,9 @@ int nfs4_replace_transport(struct nfs_server *server,
                                 const struct nfs4_fs_locations *locations);
 
 /* nfs4proc.c */
+extern int nfs4_call_sync(struct rpc_clnt *, struct nfs_server *,
+                          struct rpc_message *, struct nfs4_sequence_args *,
+                          struct nfs4_sequence_res *, int);
 extern int nfs4_proc_setclientid(struct nfs_client *, u32, unsigned short, struct rpc_cred *, struct nfs4_setclientid_res *);
 extern int nfs4_proc_setclientid_confirm(struct nfs_client *, struct nfs4_setclientid_res *arg, struct rpc_cred *);
 extern int nfs4_proc_get_rootfh(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *, bool);
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index a816f0627a6c..4dffa3a64731 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -8,6 +8,10 @@
 #include "fscache.h"
 #include "pnfs.h"
 
+#ifdef CONFIG_NFS_V4_2
+#include "nfs42.h"
+#endif
+
 #define NFSDBG_FACILITY         NFSDBG_FILE
 
 static int
@@ -115,8 +119,29 @@ nfs4_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
         return ret;
 }
 
+#ifdef CONFIG_NFS_V4_2
+static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
+{
+        loff_t ret;
+
+        switch (whence) {
+        case SEEK_HOLE:
+        case SEEK_DATA:
+                ret = nfs42_proc_llseek(filep, offset, whence);
+                if (ret != -ENOTSUPP)
+                        return ret;
+        default:
+                return nfs_file_llseek(filep, offset, whence);
+        }
+}
+#endif /* CONFIG_NFS_V4_2 */
+
 const struct file_operations nfs4_file_operations = {
+#ifdef CONFIG_NFS_V4_2
+        .llseek         = nfs4_file_llseek,
+#else
         .llseek         = nfs_file_llseek,
+#endif
         .read           = new_sync_read,
         .write          = new_sync_write,
         .read_iter      = nfs_file_read,
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7dd8aca31c29..f3a59f1fb498 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -875,7 +875,6 @@ static int nfs4_call_sync_sequence(struct rpc_clnt *clnt,
         return ret;
 }
 
-static
 int nfs4_call_sync(struct rpc_clnt *clnt,
                    struct nfs_server *server,
                    struct rpc_message *msg,
@@ -8429,7 +8428,8 @@ static const struct nfs4_minor_version_ops nfs_v4_1_minor_ops = {
                 | NFS_CAP_CHANGE_ATTR
                 | NFS_CAP_POSIX_LOCK
                 | NFS_CAP_STATEID_NFSV41
-                | NFS_CAP_ATOMIC_OPEN_V1,
+                | NFS_CAP_ATOMIC_OPEN_V1
+                | NFS_CAP_SEEK,
         .init_client = nfs41_init_client,
         .shutdown_client = nfs41_shutdown_client,
         .match_stateid = nfs41_match_stateid,
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index e13b59d8d9aa..949e8717118c 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -7427,6 +7427,10 @@ nfs4_stat_to_errno(int stat)
         return -stat;
 }
 
+#ifdef CONFIG_NFS_V4_2
+#include "nfs42xdr.c"
+#endif /* CONFIG_NFS_V4_2 */
+
 #define PROC(proc, argtype, restype)                            \
 [NFSPROC4_CLNT_##proc] = {                                      \
         .p_proc   = NFSPROC4_COMPOUND,                          \
@@ -7495,6 +7499,9 @@ struct rpc_procinfo	nfs4_procedures[] = {
                         enc_bind_conn_to_session, dec_bind_conn_to_session),
         PROC(DESTROY_CLIENTID,  enc_destroy_clientid,   dec_destroy_clientid),
 #endif /* CONFIG_NFS_V4_1 */
+#ifdef CONFIG_NFS_V4_2
+        PROC(SEEK,              enc_seek,               dec_seek),
+#endif /* CONFIG_NFS_V4_2 */
 };
 
 const struct rpc_version nfs_version4 = {