xfs: split out the remote symlink handling

The remote symlink format definition and manipulation needs to be
shared with userspace, but the in-kernel interfaces do not. Split
the remote symlink format handling out into xfs_symlink_remote.[ch]
fo it can easily be shared with userspace.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 199 insertions, 0 deletions

diff --git a/fs/xfs/xfs_symlink_remote.c b/fs/xfs/xfs_symlink_remote.c
new file mode 100644
index 000000000000..a31852471885
--- /dev/null
+++ b/fs/xfs/xfs_symlink_remote.c
@@ -0,0 +1,199 @@
+/*
+ * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * Copyright (c) 2012-2013 Red Hat, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_symlink.h"
+#include "xfs_cksum.h"
+#include "xfs_buf_item.h"
+
+
+/*
+ * Each contiguous block has a header, so it is not just a simple pathlen
+ * to FSB conversion.
+ */
+int
+xfs_symlink_blocks(
+        struct xfs_mount *mp,
+        int             pathlen)
+{
+        int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
+
+        return (pathlen + buflen - 1) / buflen;
+}
+
+int
+xfs_symlink_hdr_set(
+        struct xfs_mount        *mp,
+        xfs_ino_t               ino,
+        uint32_t                offset,
+        uint32_t                size,
+        struct xfs_buf          *bp)
+{
+        struct xfs_dsymlink_hdr *dsl = bp->b_addr;
+
+        if (!xfs_sb_version_hascrc(&mp->m_sb))
+                return 0;
+
+        dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
+        dsl->sl_offset = cpu_to_be32(offset);
+        dsl->sl_bytes = cpu_to_be32(size);
+        uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
+        dsl->sl_owner = cpu_to_be64(ino);
+        dsl->sl_blkno = cpu_to_be64(bp->b_bn);
+        bp->b_ops = &xfs_symlink_buf_ops;
+
+        return sizeof(struct xfs_dsymlink_hdr);
+}
+
+/*
+ * Checking of the symlink header is split into two parts. the verifier does
+ * CRC, location and bounds checking, the unpacking function checks the path
+ * parameters and owner.
+ */
+bool
+xfs_symlink_hdr_ok(
+        struct xfs_mount        *mp,
+        xfs_ino_t               ino,
+        uint32_t                offset,
+        uint32_t                size,
+        struct xfs_buf          *bp)
+{
+        struct xfs_dsymlink_hdr *dsl = bp->b_addr;
+
+        if (offset != be32_to_cpu(dsl->sl_offset))
+                return false;
+        if (size != be32_to_cpu(dsl->sl_bytes))
+                return false;
+        if (ino != be64_to_cpu(dsl->sl_owner))
+                return false;
+
+        /* ok */
+        return true;
+}
+
+static bool
+xfs_symlink_verify(
+        struct xfs_buf          *bp)
+{
+        struct xfs_mount        *mp = bp->b_target->bt_mount;
+        struct xfs_dsymlink_hdr *dsl = bp->b_addr;
+
+        if (!xfs_sb_version_hascrc(&mp->m_sb))
+                return false;
+        if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
+                return false;
+        if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
+                return false;
+        if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
+                return false;
+        if (be32_to_cpu(dsl->sl_offset) +
+                                be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
+                return false;
+        if (dsl->sl_owner == 0)
+                return false;
+
+        return true;
+}
+
+static void
+xfs_symlink_read_verify(
+        struct xfs_buf  *bp)
+{
+        struct xfs_mount *mp = bp->b_target->bt_mount;
+
+        /* no verification of non-crc buffers */
+        if (!xfs_sb_version_hascrc(&mp->m_sb))
+                return;
+
+        if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
+                                  offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
+            !xfs_symlink_verify(bp)) {
+                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+        }
+}
+
+static void
+xfs_symlink_write_verify(
+        struct xfs_buf  *bp)
+{
+        struct xfs_mount *mp = bp->b_target->bt_mount;
+        struct xfs_buf_log_item *bip = bp->b_fspriv;
+
+        /* no verification of non-crc buffers */
+        if (!xfs_sb_version_hascrc(&mp->m_sb))
+                return;
+
+        if (!xfs_symlink_verify(bp)) {
+                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
+                xfs_buf_ioerror(bp, EFSCORRUPTED);
+                return;
+        }
+
+        if (bip) {
+                struct xfs_dsymlink_hdr *dsl = bp->b_addr;
+                dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
+        }
+        xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
+                         offsetof(struct xfs_dsymlink_hdr, sl_crc));
+}
+
+const struct xfs_buf_ops xfs_symlink_buf_ops = {
+        .verify_read = xfs_symlink_read_verify,
+        .verify_write = xfs_symlink_write_verify,
+};
+
+void
+xfs_symlink_local_to_remote(
+        struct xfs_trans        *tp,
+        struct xfs_buf          *bp,
+        struct xfs_inode        *ip,
+        struct xfs_ifork        *ifp)
+{
+        struct xfs_mount        *mp = ip->i_mount;
+        char                    *buf;
+
+        if (!xfs_sb_version_hascrc(&mp->m_sb)) {
+                bp->b_ops = NULL;
+                memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
+                return;
+        }
+
+        /*
+         * As this symlink fits in an inode literal area, it must also fit in
+         * the smallest buffer the filesystem supports.
+         */
+        ASSERT(BBTOB(bp->b_length) >=
+                        ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
+
+        bp->b_ops = &xfs_symlink_buf_ops;
+
+        buf = bp->b_addr;
+        buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
+        memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
+}