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[PATCH 19/20] xfs: implement pNFS export operations

To: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Subject: [PATCH 19/20] xfs: implement pNFS export operations
From: Christoph Hellwig <hch@xxxxxx>
Date: Thu, 22 Jan 2015 12:10:05 +0100
Cc: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>, linux-nfs@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1421925006-24231-1-git-send-email-hch@xxxxxx>
References: <1421925006-24231-1-git-send-email-hch@xxxxxx>
Add operations to export pNFS block layouts from an XFS filesystem.  See
the previous commit adding the operations for an explanation of them.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/Makefile     |   1 +
 fs/xfs/xfs_export.c |   6 ++
 fs/xfs/xfs_fsops.c  |   2 +
 fs/xfs/xfs_iops.c   |   2 +-
 fs/xfs/xfs_iops.h   |   1 +
 fs/xfs/xfs_mount.h  |  11 +++
 fs/xfs/xfs_pnfs.c   | 243 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_pnfs.h   |  11 +++
 8 files changed, 276 insertions(+), 1 deletion(-)
 create mode 100644 fs/xfs/xfs_pnfs.c
 create mode 100644 fs/xfs/xfs_pnfs.h

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index d617999..df68285 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -121,3 +121,4 @@ xfs-$(CONFIG_XFS_POSIX_ACL) += xfs_acl.o
 xfs-$(CONFIG_PROC_FS)          += xfs_stats.o
 xfs-$(CONFIG_SYSCTL)           += xfs_sysctl.o
 xfs-$(CONFIG_COMPAT)           += xfs_ioctl32.o
+xfs-$(CONFIG_NFSD_PNFS)                += xfs_pnfs.o
diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c
index 5eb4a14..b97359b 100644
--- a/fs/xfs/xfs_export.c
+++ b/fs/xfs/xfs_export.c
@@ -30,6 +30,7 @@
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_log.h"
+#include "xfs_pnfs.h"
 
 /*
  * Note that we only accept fileids which are long enough rather than allow
@@ -245,4 +246,9 @@ const struct export_operations xfs_export_operations = {
        .fh_to_parent           = xfs_fs_fh_to_parent,
        .get_parent             = xfs_fs_get_parent,
        .commit_metadata        = xfs_fs_nfs_commit_metadata,
+#ifdef CONFIG_NFSD_PNFS
+       .get_uuid               = xfs_fs_get_uuid,
+       .map_blocks             = xfs_fs_map_blocks,
+       .commit_blocks          = xfs_fs_commit_blocks,
+#endif
 };
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 74c6211..99465ba 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -602,6 +602,8 @@ xfs_growfs_data(
        if (!mutex_trylock(&mp->m_growlock))
                return -EWOULDBLOCK;
        error = xfs_growfs_data_private(mp, in);
+       if (!error)
+               mp->m_generation++;
        mutex_unlock(&mp->m_growlock);
        return error;
 }
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index c50311c..6ff84e8 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -496,7 +496,7 @@ xfs_setattr_mode(
        inode->i_mode |= mode & ~S_IFMT;
 }
 
-static void
+void
 xfs_setattr_time(
        struct xfs_inode        *ip,
        struct iattr            *iattr)
diff --git a/fs/xfs/xfs_iops.h b/fs/xfs/xfs_iops.h
index 1c34e43..ea7a98e 100644
--- a/fs/xfs/xfs_iops.h
+++ b/fs/xfs/xfs_iops.h
@@ -32,6 +32,7 @@ extern void xfs_setup_inode(struct xfs_inode *);
  */
 #define XFS_ATTR_NOACL         0x01    /* Don't call posix_acl_chmod */
 
+extern void xfs_setattr_time(struct xfs_inode *ip, struct iattr *iattr);
 extern int xfs_setattr_nonsize(struct xfs_inode *ip, struct iattr *vap,
                               int flags);
 extern int xfs_setattr_size(struct xfs_inode *ip, struct iattr *vap);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 22ccf69..12925d5 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -175,6 +175,17 @@ typedef struct xfs_mount {
        struct workqueue_struct *m_reclaim_workqueue;
        struct workqueue_struct *m_log_workqueue;
        struct workqueue_struct *m_eofblocks_workqueue;
+
+       /*
+        * Generation of the filesysyem layout.  This is incremented by each
+        * growfs, and used by the pNFS server to ensure the client updates
+        * its view of the block device once it gets a layout that might
+        * reference the newly added blocks.  Does not need to be persistent
+        * as long as we only allow file system size increments, but if we
+        * ever support shrinks it would have to be persisted in addition
+        * to various other kinds of pain inflicted on the pNFS server.
+        */
+       __uint32_t              m_generation;
 } xfs_mount_t;
 
 /*
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
new file mode 100644
index 0000000..5d25f5d
--- /dev/null
+++ b/fs/xfs/xfs_pnfs.c
@@ -0,0 +1,243 @@
+/*
+ * Copyright (c) 2014 Christoph Hellwig.
+ */
+#include "xfs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_log.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_error.h"
+#include "xfs_iomap.h"
+#include "xfs_shared.h"
+#include "xfs_pnfs.h"
+
+int
+xfs_fs_get_uuid(
+       struct super_block      *sb,
+       u8                      *buf,
+       u32                     *len,
+       u64                     *offset)
+{
+       struct xfs_mount        *mp = XFS_M(sb);
+
+       if (*len < sizeof(uuid_t))
+               return -EINVAL;
+
+       memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
+       *len = sizeof(uuid_t);
+       *offset = offsetof(struct xfs_dsb, sb_uuid);
+       return 0;
+}
+
+static void
+xfs_bmbt_to_iomap(
+       struct xfs_inode        *ip,
+       struct iomap            *iomap,
+       struct xfs_bmbt_irec    *imap)
+{
+       struct xfs_mount        *mp = ip->i_mount;
+
+       if (imap->br_startblock == HOLESTARTBLOCK) {
+               iomap->blkno = -1;
+               iomap->type = IOMAP_HOLE;
+       } else if (imap->br_startblock == DELAYSTARTBLOCK) {
+               iomap->blkno = -1;
+               iomap->type = IOMAP_DELALLOC;
+       } else {
+               iomap->blkno = xfs_fsb_to_db(ip, imap->br_startblock);
+               if (imap->br_state == XFS_EXT_UNWRITTEN)
+                       iomap->type = IOMAP_UNWRITTEN;
+               else
+                       iomap->type = IOMAP_MAPPED;
+       }
+       iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
+       iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
+}
+
+/*
+ * Get a layout for the pNFS client.
+ */
+int
+xfs_fs_map_blocks(
+       struct inode            *inode,
+       loff_t                  offset,
+       u64                     length,
+       struct iomap            *iomap,
+       bool                    write,
+       u32                     *device_generation)
+{
+       struct xfs_inode        *ip = XFS_I(inode);
+       struct xfs_mount        *mp = ip->i_mount;
+       struct xfs_bmbt_irec    imap;
+       xfs_fileoff_t           offset_fsb, end_fsb;
+       loff_t                  limit;
+       int                     bmapi_flags = XFS_BMAPI_ENTIRE;
+       int                     nimaps = 1;
+       uint                    lock_flags;
+       int                     error = 0;
+
+       if (XFS_FORCED_SHUTDOWN(mp))
+               return -EIO;
+       if (XFS_IS_REALTIME_INODE(ip))
+               return -ENXIO;
+
+       /*
+        * Lock out any other I/O before we flush and invalidate the pagecache,
+        * and then hand out a layout to the remote system.  This is very
+        * similar to direct I/O, except that the synchronization is much more
+        * complicated.  See the comment near xfs_break_layouts for a detailed
+        * explanation.
+        */
+       xfs_ilock(ip, XFS_IOLOCK_EXCL);
+
+       error = -EINVAL;
+       limit = mp->m_super->s_maxbytes;
+       if (!write)
+               limit = max(limit, round_up(i_size_read(inode),
+                                    inode->i_sb->s_blocksize));
+       if (offset > limit)
+               goto out_unlock;
+       if (offset > limit - length)
+               length = limit - offset;
+
+       error = filemap_write_and_wait(inode->i_mapping);
+       if (error)
+               goto out_unlock;
+       error = invalidate_inode_pages2(inode->i_mapping);
+       if (WARN_ON_ONCE(error))
+               return error;
+
+       end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
+       offset_fsb = XFS_B_TO_FSBT(mp, offset);
+
+       lock_flags = xfs_ilock_data_map_shared(ip);
+       error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
+                               &imap, &nimaps, bmapi_flags);
+       xfs_iunlock(ip, lock_flags);
+
+       if (error)
+               goto out_unlock;
+
+       if (write) {
+               enum xfs_prealloc_flags flags = 0;
+
+               ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
+
+               if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
+                       error = xfs_iomap_write_direct(ip, offset, length,
+                                                      &imap, nimaps);
+                       if (error)
+                               goto out_unlock;
+
+                       /*
+                        * Ensure the next transaction is committed
+                        * synchronously so that the blocks allocated and
+                        * handed out to the client are guaranteed to be
+                        * present even after a server crash.
+                        */
+                       flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
+               }
+
+               error = xfs_update_prealloc_flags(ip, flags);
+               if (error)
+                       goto out_unlock;
+       }
+       xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+
+       xfs_bmbt_to_iomap(ip, iomap, &imap);
+       *device_generation = mp->m_generation;
+       return error;
+out_unlock:
+       xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+       return error;
+}
+
+/*
+ * Make sure the blocks described by maps are stable on disk.  This includes
+ * converting any unwritten extents, flushing the disk cache and updating the
+ * time stamps.
+ *
+ * Note that we rely on the caller to always send us a timestamp update so that
+ * we always commit a transaction here.  If that stops being true we will have
+ * to manually flush the cache here similar to what the fsync code path does
+ * for datasyncs on files that have no dirty metadata.
+ */
+int
+xfs_fs_commit_blocks(
+       struct inode            *inode,
+       struct iomap            *maps,
+       int                     nr_maps,
+       struct iattr            *iattr)
+{
+       struct xfs_inode        *ip = XFS_I(inode);
+       struct xfs_mount        *mp = ip->i_mount;
+       struct xfs_trans        *tp;
+       int                     error, i;
+       loff_t                  size;
+
+       ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
+
+       xfs_ilock(ip, XFS_IOLOCK_EXCL);
+
+       size = i_size_read(inode);
+       if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size)
+               size = iattr->ia_size;
+
+       for (i = 0; i < nr_maps; i++) {
+               u64 start, length, end;
+
+               start = maps[i].offset;
+               if (start > size)
+                       continue;
+
+               end = start + maps[i].length;
+               if (end > size)
+                       end = size;
+
+               length = end - start;
+               if (!length)
+                       continue;
+       
+               /*
+                * Make sure reads through the pagecache see the new data.
+                */
+               error = invalidate_inode_pages2_range(inode->i_mapping,
+                                       start >> PAGE_CACHE_SHIFT,
+                                       (end - 1) >> PAGE_CACHE_SHIFT);
+               WARN_ON_ONCE(error);
+
+               error = xfs_iomap_write_unwritten(ip, start, length);
+               if (error)
+                       goto out_drop_iolock;
+       }
+
+       tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
+       error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
+       if (error)
+               goto out_drop_iolock;
+
+       xfs_ilock(ip, XFS_ILOCK_EXCL);
+       xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+       xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+       xfs_setattr_time(ip, iattr);
+       if (iattr->ia_valid & ATTR_SIZE) {
+               if (iattr->ia_size > i_size_read(inode)) {
+                       i_size_write(inode, iattr->ia_size);
+                       ip->i_d.di_size = iattr->ia_size;
+               }
+       }
+
+       xfs_trans_set_sync(tp);
+       error = xfs_trans_commit(tp, 0);
+
+out_drop_iolock:
+       xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+       return error;
+}
diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
new file mode 100644
index 0000000..0d91255
--- /dev/null
+++ b/fs/xfs/xfs_pnfs.h
@@ -0,0 +1,11 @@
+#ifndef _XFS_PNFS_H
+#define _XFS_PNFS_H 1
+
+#ifdef CONFIG_NFSD_PNFS
+int xfs_fs_get_uuid(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
+int xfs_fs_map_blocks(struct inode *inode, loff_t offset, u64 length,
+               struct iomap *iomap, bool write, u32 *device_generation);
+int xfs_fs_commit_blocks(struct inode *inode, struct iomap *maps, int nr_maps,
+               struct iattr *iattr);
+#endif /* CONFIG_NFSD_PNFS */
+#endif /* _XFS_PNFS_H */
-- 
1.9.1

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