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[PATCH 30/58] xfs: implement XFS_IOC_SWAPEXT when rmap btree is enabled

To: david@xxxxxxxxxxxxx, darrick.wong@xxxxxxxxxx
Subject: [PATCH 30/58] xfs: implement XFS_IOC_SWAPEXT when rmap btree is enabled
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Tue, 06 Oct 2015 21:58:25 -0700
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20151007045443.30457.47038.stgit@xxxxxxxxxxxxxxxx>
References: <20151007045443.30457.47038.stgit@xxxxxxxxxxxxxxxx>
User-agent: StGit/0.17.1-dirty
Implement extent swapping when reverse-mapping is enabled.

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_btree.c      |   17 ++++++
 fs/xfs/libxfs/xfs_rmap.c       |  112 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_rmap_btree.h |    8 +++
 fs/xfs/xfs_bmap_util.c         |   38 +++++++++-----
 4 files changed, 161 insertions(+), 14 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 13971c6..2d7dc8c 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -32,6 +32,7 @@
 #include "xfs_trace.h"
 #include "xfs_cksum.h"
 #include "xfs_alloc.h"
+#include "xfs_rmap_btree.h"
 
 /*
  * Cursor allocation zone.
@@ -3988,6 +3989,8 @@ xfs_btree_block_change_owner(
        struct xfs_btree_block  *block;
        struct xfs_buf          *bp;
        union xfs_btree_ptr     rptr;
+       struct xfs_owner_info   old_oinfo, new_oinfo;
+       int                     error;
 
        /* do right sibling readahead */
        xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
@@ -3999,6 +4002,20 @@ xfs_btree_block_change_owner(
        else
                block->bb_u.s.bb_owner = cpu_to_be32(new_owner);
 
+       /* change rmap owners (bmbt blocks only) */
+       if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
+               XFS_RMAP_INO_BMBT_OWNER(&old_oinfo,
+                               cur->bc_private.b.ip->i_ino,
+                               cur->bc_private.b.whichfork);
+               XFS_RMAP_INO_BMBT_OWNER(&new_oinfo,
+                               new_owner,
+                               cur->bc_private.b.whichfork);
+               error = xfs_rmap_change_bmbt_owner(cur, bp, &old_oinfo,
+                               &new_oinfo);
+               if (error)
+                       return error;
+       }
+
        /*
         * If the block is a root block hosted in an inode, we might not have a
         * buffer pointer here and we shouldn't attempt to log the change as the
diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index d821b1a..b2781f5 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -35,6 +35,8 @@
 #include "xfs_trace.h"
 #include "xfs_error.h"
 #include "xfs_extent_busy.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_btree.h"
 
 /*
  * Lookup the first record less than or equal to [bno, len, owner, offset]
@@ -859,3 +861,113 @@ xfs_rmap_resize(
 done:
        return error;
 }
+
+/**
+ * Change ownership of a file's BMBT block reverse-mappings.
+ */
+int
+xfs_rmap_change_bmbt_owner(
+       struct xfs_btree_cur    *bcur,
+       struct xfs_buf          *bp,
+       struct xfs_owner_info   *old_owner,
+       struct xfs_owner_info   *new_owner)
+{
+       struct xfs_buf          *agfbp;
+       xfs_fsblock_t           fsbno;
+       xfs_agnumber_t          agno;
+       xfs_agblock_t           agbno;
+       int                     error;
+
+       if (!xfs_sb_version_hasrmapbt(&bcur->bc_mp->m_sb) || !bp)
+               return 0;
+
+       fsbno = XFS_DADDR_TO_FSB(bcur->bc_mp, XFS_BUF_ADDR(bp));
+       agno = XFS_FSB_TO_AGNO(bcur->bc_mp, fsbno);
+       agbno = XFS_FSB_TO_AGBNO(bcur->bc_mp, fsbno);
+
+       error = xfs_read_agf(bcur->bc_mp, bcur->bc_tp, agno, 0, &agfbp);
+
+       error = xfs_rmap_free(bcur->bc_tp, agfbp, agno, agbno, 1, old_owner);
+       if (error)
+               goto err;
+
+       error = xfs_rmap_alloc(bcur->bc_tp, agfbp, agno, agbno, 1, new_owner);
+       if (error)
+               goto err;
+
+err:
+       xfs_trans_brelse(bcur->bc_tp, agfbp);
+       return error;
+}
+
+/**
+ * Change the ownership on a file's extent's reverse-mappings.
+ */
+int
+xfs_rmap_change_extent_owner(
+       struct xfs_mount        *mp,
+       struct xfs_inode        *ip,
+       xfs_ino_t               ino,
+       xfs_fileoff_t           isize,
+       struct xfs_trans        *tp,
+       int                     whichfork,
+       xfs_ino_t               new_owner)
+{
+       struct xfs_bmbt_irec    imap;
+       struct xfs_btree_cur    *cur = NULL;
+       struct xfs_buf          *agfbp = NULL;
+       int                     nimaps;
+       xfs_fileoff_t           offset;
+       xfs_filblks_t           len;
+       xfs_agnumber_t          agno;
+       int                     flags = 0;
+       int                     error;
+
+       if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+               return 0;
+
+       if (whichfork == XFS_ATTR_FORK)
+               flags |= XFS_BMAPI_ATTRFORK;
+
+       offset = 0;
+       len = XFS_B_TO_FSB(mp, isize);
+       nimaps = 1;
+       error = xfs_bmapi_read(ip, offset, len, &imap, &nimaps, flags);
+       while (error == 0 && nimaps > 0) {
+               if (imap.br_startblock == HOLESTARTBLOCK ||
+                   imap.br_startblock == DELAYSTARTBLOCK)
+                       goto advloop;
+
+               agno = XFS_FSB_TO_AGNO(mp, imap.br_startblock);
+
+               error = xfs_read_agf(mp, tp, agno, 0, &agfbp);
+               if (error)
+                       break;
+
+               cur = xfs_rmapbt_init_cursor(mp, tp, agfbp, agno);
+
+               error = xfs_rmap_delete(cur, ino, whichfork, &imap);
+               if (error)
+                       break;
+               error = xfs_rmap_insert(cur, new_owner, whichfork, &imap);
+               if (error)
+                       break;
+
+               xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+               cur = NULL;
+               xfs_trans_brelse(tp, agfbp);
+               agfbp = NULL;
+advloop:
+               offset += imap.br_blockcount;
+               len -= imap.br_blockcount;
+               nimaps = 1;
+               error = xfs_bmapi_read(ip, offset, len, &imap, &nimaps, flags);
+       }
+
+       if (cur)
+               xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR :
+                                         XFS_BTREE_NOERROR);
+       if (agfbp)
+               xfs_trans_brelse(tp, agfbp);
+       return error;
+}
diff --git a/fs/xfs/libxfs/xfs_rmap_btree.h b/fs/xfs/libxfs/xfs_rmap_btree.h
index 0131d9a..5d248b5 100644
--- a/fs/xfs/libxfs/xfs_rmap_btree.h
+++ b/fs/xfs/libxfs/xfs_rmap_btree.h
@@ -88,4 +88,12 @@ int xfs_rmap_slide(struct xfs_btree_cur *rcur, xfs_ino_t 
ino, int whichfork,
 int xfs_rmap_resize(struct xfs_btree_cur *rcur, xfs_ino_t ino, int whichfork,
                struct xfs_bmbt_irec *PREV, long size_adj);
 
+/* functions for changing rmap ownership */
+int xfs_rmap_change_extent_owner(struct xfs_mount *mp, struct xfs_inode *ip,
+               xfs_ino_t ino, xfs_fileoff_t isize, struct xfs_trans *tp,
+               int whichfork, xfs_ino_t new_owner);
+int xfs_rmap_change_bmbt_owner(struct xfs_btree_cur *bcur, struct xfs_buf *bp,
+               struct xfs_owner_info *old_owner,
+               struct xfs_owner_info *new_owner);
+
 #endif /* __XFS_RMAP_BTREE_H__ */
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index f41a6f7..245a34a 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -40,6 +40,7 @@
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_log.h"
+#include "xfs_rmap_btree.h"
 
 /* Kernel only BMAP related definitions and functions */
 
@@ -1668,6 +1669,17 @@ xfs_swap_extent_flush(
        return 0;
 }
 
+static int
+change_extent_owner(
+       struct xfs_inode        *ip,
+       struct xfs_trans        *tp,
+       int                     whichfork,
+       struct xfs_inode        *tip)
+{
+       return xfs_rmap_change_extent_owner(ip->i_mount, ip, ip->i_ino,
+                       ip->i_d.di_size, tp, whichfork, tip->i_ino);
+}
+
 int
 xfs_swap_extents(
        xfs_inode_t     *ip,    /* target inode */
@@ -1684,19 +1696,7 @@ xfs_swap_extents(
        int             taforkblks = 0;
        __uint64_t      tmp;
        int             lock_flags;
-
-       /*
-        * We can't swap extents on rmap btree enabled filesystems yet
-        * as there is no mechanism to update the owner of extents in
-        * the rmap tree yet. Hence, for the moment, just reject attempts
-        * to swap extents with EINVAL after emitting a warning once to remind
-        * us this needs fixing.
-        */
-       if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
-               WARN_ONCE(1,
-       "XFS: XFS_IOC_SWAPEXT not supported on RMAP enabled filesystems\n");
-               return -EINVAL;
-       }
+       struct xfs_trans_res    tres = {.tr_logres = 262144, .tr_logcount = 1, 
.tr_logflags = 0};
 
        tempifp = kmem_alloc(sizeof(xfs_ifork_t), KM_MAYFAIL);
        if (!tempifp) {
@@ -1734,7 +1734,9 @@ xfs_swap_extents(
                goto out_unlock;
 
        tp = xfs_trans_alloc(mp, XFS_TRANS_SWAPEXT);
-       error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
+       /* XXX How do we create a potentially huge transaction here? */
+       /* error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0); */
+       error = xfs_trans_reserve(tp, &tres, 0, 0);
        if (error) {
                xfs_trans_cancel(tp);
                goto out_unlock;
@@ -1834,6 +1836,14 @@ xfs_swap_extents(
                        goto out_trans_cancel;
        }
 
+       /* Change owners in the extent rmaps */
+       error = change_extent_owner(ip, tp, XFS_DATA_FORK, tip);
+       if (error)
+               goto out_trans_cancel;
+       error = change_extent_owner(tip, tp, XFS_DATA_FORK, ip);
+       if (error)
+               goto out_trans_cancel;
+
        /*
         * Swap the data forks of the inodes
         */

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