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[PATCH 02/10] XFS: Use struct inodes instead of vnodes to kill vn_grab

To: xfs@xxxxxxxxxxx
Subject: [PATCH 02/10] XFS: Use struct inodes instead of vnodes to kill vn_grab
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 8 Oct 2008 08:43:31 +1100
In-reply-to: <1223415819-6599-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1223415819-6599-1-git-send-email-david@xxxxxxxxxxxxx>
With the sync code relocated to the linux-2.6 directory we can use
struct inodes directly. If we do the same thing for the quota
release code, we can remove vn_grab altogether.  While here, convert
the VN_BAD() checks to is_bad_inode() so we can remove vnodes
entirely from this code.

Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>
---
 fs/xfs/linux-2.6/xfs_sync.c    |   53 +++++++++++++++++++--------------------
 fs/xfs/linux-2.6/xfs_vnode.c   |    6 ++--
 fs/xfs/linux-2.6/xfs_vnode.h   |    5 ----
 fs/xfs/quota/xfs_qm_syscalls.c |   16 ++++++------
 4 files changed, 37 insertions(+), 43 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 59da332..461c1dc 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -131,10 +131,7 @@ xfs_sync_inodes_ag(
        int             flags,
        int             *bypassed)
 {
-       xfs_inode_t     *ip = NULL;
-       struct inode    *vp = NULL;
        xfs_perag_t     *pag = &mp->m_perag[ag];
-       boolean_t       vnode_refed = B_FALSE;
        int             nr_found;
        int             first_index = 0;
        int             error = 0;
@@ -156,6 +153,10 @@ xfs_sync_inodes_ag(
        }
 
        do {
+               struct inode    *inode;
+               boolean_t       inode_refed;
+               xfs_inode_t     *ip = NULL;
+
                /*
                 * use a gang lookup to find the next inode in the tree
                 * as the tree is sparse and a gang lookup walks to find
@@ -177,14 +178,14 @@ xfs_sync_inodes_ag(
                 * skip inodes in reclaim. Let xfs_syncsub do that for
                 * us so we don't need to worry.
                 */
-               vp = VFS_I(ip);
-               if (!vp) {
+               if (xfs_iflags_test(ip, (XFS_IRECLAIM|XFS_IRECLAIMABLE))) {
                        read_unlock(&pag->pag_ici_lock);
                        continue;
                }
 
                /* bad inodes are dealt with elsewhere */
-               if (VN_BAD(vp)) {
+               inode = VFS_I(ip);
+               if (is_bad_inode(inode)) {
                        read_unlock(&pag->pag_ici_lock);
                        continue;
                }
@@ -196,30 +197,29 @@ xfs_sync_inodes_ag(
                }
 
                /*
-                * The inode lock here actually coordinates with the almost
-                * spurious inode lock in xfs_ireclaim() to prevent the vnode
-                * we handle here without a reference from being freed while we
-                * reference it.  If we lock the inode while it's on the mount
-                * list here, then the spurious inode lock in xfs_ireclaim()
-                * after the inode is pulled from the mount list will sleep
-                * until we release it here.  This keeps the vnode from being
-                * freed while we reference it.
+                * If we can't get a reference on the VFS_I, the inode must be
+                * in reclaim. If we can get the inode lock without blocking,
+                * it is safe to flush the inode because we hold the tree lock
+                * and xfs_iextract will block right now. Hence if we lock the
+                * inode while holding the tree lock, xfs_ireclaim() is
+                * guaranteed to block on the inode lock we now hold and hence
+                * it is safe to reference the inode until we drop the inode
+                * locks completely.
                 */
-               if (xfs_ilock_nowait(ip, lock_flags) == 0) {
-                       vp = vn_grab(vp);
+               inode_refed = B_FALSE;
+               if (igrab(inode)) {
                        read_unlock(&pag->pag_ici_lock);
-                       if (!vp)
-                               continue;
                        xfs_ilock(ip, lock_flags);
-
-                       ASSERT(vp == VFS_I(ip));
-                       ASSERT(ip->i_mount == mp);
-
-                       vnode_refed = B_TRUE;
+                       inode_refed = B_TRUE;
                } else {
-                       /* safe to unlock here as we have a reference */
+                       if (!xfs_ilock_nowait(ip, lock_flags)) {
+                               /* leave it to reclaim */
+                               read_unlock(&pag->pag_ici_lock);
+                               continue;
+                       }
                        read_unlock(&pag->pag_ici_lock);
                }
+
                /*
                 * If we have to flush data or wait for I/O completion
                 * we need to drop the ilock that we currently hold.
@@ -240,7 +240,7 @@ xfs_sync_inodes_ag(
                        xfs_ilock(ip, XFS_ILOCK_SHARED);
                }
 
-               if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
+               if ((flags & SYNC_DELWRI) && VN_DIRTY(inode)) {
                        xfs_iunlock(ip, XFS_ILOCK_SHARED);
                        error = xfs_flush_pages(ip, 0, -1, fflag, FI_NONE);
                        if (flags & SYNC_IOWAIT)
@@ -268,9 +268,8 @@ xfs_sync_inodes_ag(
                if (lock_flags)
                        xfs_iunlock(ip, lock_flags);
 
-               if (vnode_refed) {
+               if (inode_refed) {
                        IRELE(ip);
-                       vnode_refed = B_FALSE;
                }
 
                if (error)
diff --git a/fs/xfs/linux-2.6/xfs_vnode.c b/fs/xfs/linux-2.6/xfs_vnode.c
index b52528b..dceb6db 100644
--- a/fs/xfs/linux-2.6/xfs_vnode.c
+++ b/fs/xfs/linux-2.6/xfs_vnode.c
@@ -90,10 +90,10 @@ vn_ioerror(
  */
 static inline int xfs_icount(struct xfs_inode *ip)
 {
-       struct inode *vp = VFS_I(ip);
+       struct inode *inode = VFS_I(ip);
 
-       if (vp)
-               return vn_count(vp);
+       if (!inode)
+               return atomic_read(&inode->i_count);
        return -1;
 }
 
diff --git a/fs/xfs/linux-2.6/xfs_vnode.h b/fs/xfs/linux-2.6/xfs_vnode.h
index 683ce16..bf89e41 100644
--- a/fs/xfs/linux-2.6/xfs_vnode.h
+++ b/fs/xfs/linux-2.6/xfs_vnode.h
@@ -80,11 +80,6 @@ do { \
        iput(VFS_I(ip)); \
 } while (0)
 
-static inline struct inode *vn_grab(struct inode *vp)
-{
-       return igrab(vp);
-}
-
 /*
  * Dealing with bad inodes
  */
diff --git a/fs/xfs/quota/xfs_qm_syscalls.c b/fs/xfs/quota/xfs_qm_syscalls.c
index 26152b9..4254b07 100644
--- a/fs/xfs/quota/xfs_qm_syscalls.c
+++ b/fs/xfs/quota/xfs_qm_syscalls.c
@@ -1031,13 +1031,13 @@ xfs_qm_dqrele_inodes_ag(
        uint            flags)
 {
        xfs_inode_t     *ip = NULL;
-       struct inode    *vp = NULL;
        xfs_perag_t     *pag = &mp->m_perag[ag];
        int             first_index = 0;
        int             nr_found;
 
        do {
-               boolean_t       vnode_refd = B_FALSE;
+               boolean_t       inode_refed;
+               struct inode    *inode;
 
                /*
                 * use a gang lookup to find the next inode in the tree
@@ -1057,19 +1057,19 @@ xfs_qm_dqrele_inodes_ag(
                first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
 
                /* skip quota inodes and those in reclaim */
-               vp = VFS_I(ip);
-               if (!vp || ip == XFS_QI_UQIP(mp) || ip == XFS_QI_GQIP(mp)) {
+               inode = VFS_I(ip);
+               if (!inode || ip == XFS_QI_UQIP(mp) || ip == XFS_QI_GQIP(mp)) {
                        ASSERT(ip->i_udquot == NULL);
                        ASSERT(ip->i_gdquot == NULL);
                        read_unlock(&pag->pag_ici_lock);
                        continue;
                }
                if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0) {
-                       vp = vn_grab(vp);
+                       inode = igrab(inode);
                        read_unlock(&pag->pag_ici_lock);
-                       if (!vp)
+                       if (!inode)
                                continue;
-                       vnode_refd = B_TRUE;
+                       inode_refed = B_TRUE;
                        xfs_ilock(ip, XFS_ILOCK_EXCL);
                } else {
                        read_unlock(&pag->pag_ici_lock);
@@ -1084,7 +1084,7 @@ xfs_qm_dqrele_inodes_ag(
                        ip->i_gdquot = NULL;
                }
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
-               if (vnode_refd)
+               if (inode_refed)
                        IRELE(ip);
        } while (nr_found);
 }
-- 
1.5.6.5

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