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[PATCH 1/9] xfs: fix extent format buffer allocation size

To: xfs@xxxxxxxxxxx
Subject: [PATCH 1/9] xfs: fix extent format buffer allocation size
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 6 Apr 2011 16:19:10 +1000
In-reply-to: <1302070758-17312-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1302070758-17312-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

When formatting an inode item, we have to allocate a separate buffer
to hold extents when there are delayed allocation extents on the
inode and it is in extent format. The allocation size is derived
from the in-core data fork representation, which accounts for
delayed allocation extents, while the on-disk representation does
not contain any delalloc extents.

As a result of this mismatch, the allocated buffer can be far larger
than needed to hold the real extent list which, due to the fact the
inode is in extent format, is limited to the size of the literal
area of the inode. However, we can have thousands of delalloc
extents, resulting in an allocation size orders of magnitude larger
than is needed to hold all the real extents.

Fix this by limiting the size of the buffer being allocated to the
size of the literal area of the inodes in the filesystem (i.e. the
maximum size an inode fork can grow to).

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Alex Elder <aelder@xxxxxxx>
---
 fs/xfs/xfs_inode_item.c |   68 ++++++++++++++++++++++++++++------------------
 1 files changed, 41 insertions(+), 27 deletions(-)

diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 46cc401..7cfdb10 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -198,6 +198,42 @@ xfs_inode_item_size(
 }
 
 /*
+ * xfs_inode_item_format_extents - convert in-core extents to on-disk form
+ *
+ * For either the data or attr fork in extent format, we need to endian convert
+ * the in-core extent as we place them into the on-disk inode. In this case, we
+ * need to do this conversion before we write the extents into the log. Because
+ * we don't have the disk inode to write into here, we allocate a buffer and
+ * format the extents into it via xfs_iextents_copy(). We free the buffer in
+ * the unlock routine after the copy for the log has been made.
+ *
+ * In the case of the data fork, the in-core and on-disk fork sizes can be
+ * different due to delayed allocation extents. We only log on-disk extents
+ * here, so always use the physical fork size to determine the size of the
+ * buffer we need to allocate.
+ */
+STATIC void
+xfs_inode_item_format_extents(
+       struct xfs_inode        *ip,
+       struct xfs_log_iovec    *vecp,
+       int                     whichfork,
+       int                     type)
+{
+       xfs_bmbt_rec_t          *ext_buffer;
+
+       ext_buffer = kmem_alloc(XFS_IFORK_SIZE(ip, whichfork),
+                                                       KM_SLEEP | KM_NOFS);
+       if (whichfork == XFS_DATA_FORK)
+               ip->i_itemp->ili_extents_buf = ext_buffer;
+       else
+               ip->i_itemp->ili_aextents_buf = ext_buffer;
+
+       vecp->i_addr = ext_buffer;
+       vecp->i_len = xfs_iextents_copy(ip, ext_buffer, whichfork);
+       vecp->i_type = type;
+}
+
+/*
  * This is called to fill in the vector of log iovecs for the
  * given inode log item.  It fills the first item with an inode
  * log format structure, the second with the on-disk inode structure,
@@ -213,7 +249,6 @@ xfs_inode_item_format(
        struct xfs_inode        *ip = iip->ili_inode;
        uint                    nvecs;
        size_t                  data_bytes;
-       xfs_bmbt_rec_t          *ext_buffer;
        xfs_mount_t             *mp;
 
        vecp->i_addr = &iip->ili_format;
@@ -320,22 +355,8 @@ xfs_inode_item_format(
                        } else
 #endif
                        {
-                               /*
-                                * There are delayed allocation extents
-                                * in the inode, or we need to convert
-                                * the extents to on disk format.
-                                * Use xfs_iextents_copy()
-                                * to copy only the real extents into
-                                * a separate buffer.  We'll free the
-                                * buffer in the unlock routine.
-                                */
-                               ext_buffer = kmem_alloc(ip->i_df.if_bytes,
-                                       KM_SLEEP);
-                               iip->ili_extents_buf = ext_buffer;
-                               vecp->i_addr = ext_buffer;
-                               vecp->i_len = xfs_iextents_copy(ip, ext_buffer,
-                                               XFS_DATA_FORK);
-                               vecp->i_type = XLOG_REG_TYPE_IEXT;
+                               xfs_inode_item_format_extents(ip, vecp,
+                                       XFS_DATA_FORK, XLOG_REG_TYPE_IEXT);
                        }
                        ASSERT(vecp->i_len <= ip->i_df.if_bytes);
                        iip->ili_format.ilf_dsize = vecp->i_len;
@@ -445,19 +466,12 @@ xfs_inode_item_format(
                         */
                        vecp->i_addr = ip->i_afp->if_u1.if_extents;
                        vecp->i_len = ip->i_afp->if_bytes;
+                       vecp->i_type = XLOG_REG_TYPE_IATTR_EXT;
 #else
                        ASSERT(iip->ili_aextents_buf == NULL);
-                       /*
-                        * Need to endian flip before logging
-                        */
-                       ext_buffer = kmem_alloc(ip->i_afp->if_bytes,
-                               KM_SLEEP);
-                       iip->ili_aextents_buf = ext_buffer;
-                       vecp->i_addr = ext_buffer;
-                       vecp->i_len = xfs_iextents_copy(ip, ext_buffer,
-                                       XFS_ATTR_FORK);
+                       xfs_inode_item_format_extents(ip, vecp,
+                                       XFS_ATTR_FORK, XLOG_REG_TYPE_IATTR_EXT);
 #endif
-                       vecp->i_type = XLOG_REG_TYPE_IATTR_EXT;
                        iip->ili_format.ilf_asize = vecp->i_len;
                        vecp++;
                        nvecs++;
-- 
1.7.2.3

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