[PATCH 05/13] RFC: nfs: ask for layouttypes during fsinfo call

Fred Isaman
2010-09-09T18:10:37Z

From: The pNFS Team <linux-nfs@vger.kernel.org>

This information will be used to determine which layout driver,
if any, to use for subsequent IO on this filesystem. Each driver
is assigned an integer id, with 0 reserved to indicate no driver.

The server can in theory return multiple ids. However, our current
client implementation only notes the first entry and ignores the
rest.

Signed-off-by: TBD - melding/reorganization of several patches
---
fs/nfs/nfs4proc.c | 2 +-
fs/nfs/nfs4xdr.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/nfs_xdr.h | 1 +
3 files changed, 59 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 089da5b..9e6b086 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -129,7 +129,7 @@ const u32 nfs4_fsinfo_bitmap[2] = { FATTR4_WORD0_MAXFILESIZE
| FATTR4_WORD0_MAXREAD
| FATTR4_WORD0_MAXWRITE
| FATTR4_WORD0_LEASE_TIME,
- 0
+ FATTR4_WORD1_FS_LAYOUT_TYPES
};

const u32 nfs4_fs_locations_bitmap[2] = {
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 08ef912..60233ae 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3868,6 +3868,60 @@ xdr_error:
return status;
}

+/*
+ * Decode potentially multiple layout types. Currently we only support
+ * one layout driver per file system.
+ */
+static int decode_first_pnfs_layout_type(struct xdr_stream *xdr,
+ uint32_t *layouttype)
+{
+ uint32_t *p;
+ int num;
+
+ p = xdr_inline_decode(xdr, 4);
+ if (unlikely(!p))
+ goto out_overflow;
+ num = be32_to_cpup(p);
+
+ /* pNFS is not supported by the underlying file system */
+ if (num == 0) {
+ *layouttype = 0;
+ return 0;
+ }
+ if (num > 1)
+ printk(KERN_INFO "%s: Warning: Multiple pNFS layout drivers "
+ "per filesystem not supported\n", __func__);
+
+ /* Decode and set first layout type, move xdr->p past unused types */
+ p = xdr_inline_decode(xdr, num * 4);
+ if (unlikely(!p))
+ goto out_overflow;
+ *layouttype = be32_to_cpup(p);
+ return 0;
+out_overflow:
+ print_overflow_msg(__func__, xdr);
+ return -EIO;
+}
+
+/*
+ * The type of file system exported.
+ * Note we must ensure that layouttype is set in any non-error case.
+ */
+static int decode_attr_pnfstype(struct xdr_stream *xdr, uint32_t *bitmap,
+ uint32_t *layouttype)
+{
+ int status = 0;
+
+ dprintk("%s: bitmap is %x\n", __func__, bitmap[1]);
+ if (unlikely(bitmap[1] & (FATTR4_WORD1_FS_LAYOUT_TYPES - 1U)))
+ return -EIO;
+ if (bitmap[1] & FATTR4_WORD1_FS_LAYOUT_TYPES) {
+ status = decode_first_pnfs_layout_type(xdr, layouttype);
+ bitmap[1] &= ~FATTR4_WORD1_FS_LAYOUT_TYPES;
+ } else
+ *layouttype = 0;
+ return status;
+}

static int decode_fsinfo(struct xdr_stream *xdr, struct nfs_fsinfo *fsinfo)
{
@@ -3894,6 +3948,9 @@ static int decode_fsinfo(struct xdr_stream *xdr, struct nfs_fsinfo *fsinfo)
if ((status = decode_attr_maxwrite(xdr, bitmap, &fsinfo->wtmax)) != 0)
goto xdr_error;
fsinfo->wtpref = fsinfo->wtmax;
+ status = decode_attr_pnfstype(xdr, bitmap, &fsinfo->layouttype);
+ if (status)
+ goto xdr_error;

status = verify_attr_len(xdr, savep, attrlen);
xdr_error:
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index fc46192..8a2c228 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -113,6 +113,7 @@ struct nfs_fsinfo {
__u32 dtpref; /* pref. readdir transfer size */
__u64 maxfilesize;
__u32 lease_time; /* in seconds */
+ __u32 layouttype; /* supported pnfs layout driver */
};

struct nfs_fsstat {
--
1.7.2.1