[XFS] Use the inode tree for finding dirty inodes

Update xfs_sync_inodes to walk the inode radix tree cache to find dirty
inodes. This removes a huge bunch of nasty, messy code for traversing the
mount inode list safely and removes another user of the mount inode list.

Version 3 o rediff against new linux-2.6/xfs_sync.c code

Version 2 o add comment explaining use of gang lookups for a single inode
o use IRELE, not VN_RELE o move check for ag initialisation to caller.

SGI-PV: 988139

SGI-Modid: xfs-linux-melb:xfs-kern:32290a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

1 files changed, 101 insertions, 260 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index cd82ba523dc4..53d85ecb1d50 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -121,356 +121,197 @@ xfs_sync(
 }
 
 /*
- * xfs sync routine for internal use
- *
- * This routine supports all of the flags defined for the generic vfs_sync
- * interface as explained above under xfs_sync.
- *
+ * Sync all the inodes in the given AG according to the
+ * direction given by the flags.
  */
-int
-xfs_sync_inodes(
+STATIC int
+xfs_sync_inodes_ag(
         xfs_mount_t     *mp,
+        int             ag,
         int             flags,
-        int             *bypassed)
+        int             *bypassed)
 {
         xfs_inode_t     *ip = NULL;
         struct inode    *vp = NULL;
-        int             error;
-        int             last_error;
-        uint64_t        fflag;
-        uint            lock_flags;
-        uint            base_lock_flags;
-        boolean_t       mount_locked;
-        boolean_t       vnode_refed;
-        int             preempt;
-        xfs_iptr_t      *ipointer;
-#ifdef DEBUG
-        boolean_t       ipointer_in = B_FALSE;
-
-#define IPOINTER_SET    ipointer_in = B_TRUE
-#define IPOINTER_CLR    ipointer_in = B_FALSE
-#else
-#define IPOINTER_SET
-#define IPOINTER_CLR
-#endif
-
-
-/* Insert a marker record into the inode list after inode ip. The list
- * must be locked when this is called. After the call the list will no
- * longer be locked.
- */
-#define IPOINTER_INSERT(ip, mp) { \
-                ASSERT(ipointer_in == B_FALSE); \
-                ipointer->ip_mnext = ip->i_mnext; \
-                ipointer->ip_mprev = ip; \
-                ip->i_mnext = (xfs_inode_t *)ipointer; \
-                ipointer->ip_mnext->i_mprev = (xfs_inode_t *)ipointer; \
-                preempt = 0; \
-                XFS_MOUNT_IUNLOCK(mp); \
-                mount_locked = B_FALSE; \
-                IPOINTER_SET; \
-        }
-
-/* Remove the marker from the inode list. If the marker was the only item
- * in the list then there are no remaining inodes and we should zero out
- * the whole list. If we are the current head of the list then move the head
- * past us.
- */
-#define IPOINTER_REMOVE(ip, mp) { \
-                ASSERT(ipointer_in == B_TRUE); \
-                if (ipointer->ip_mnext != (xfs_inode_t *)ipointer) { \
-                        ip = ipointer->ip_mnext; \
-                        ip->i_mprev = ipointer->ip_mprev; \
-                        ipointer->ip_mprev->i_mnext = ip; \
-                        if (mp->m_inodes == (xfs_inode_t *)ipointer) { \
-                                mp->m_inodes = ip; \
-                        } \
-                } else { \
-                        ASSERT(mp->m_inodes == (xfs_inode_t *)ipointer); \
-                        mp->m_inodes = NULL; \
-                        ip = NULL; \
-                } \
-                IPOINTER_CLR; \
-        }
-
-#define XFS_PREEMPT_MASK        0x7f
-
-        ASSERT(!(flags & SYNC_BDFLUSH));
-
-        if (bypassed)
-                *bypassed = 0;
-        if (mp->m_flags & XFS_MOUNT_RDONLY)
-                return 0;
-        error = 0;
-        last_error = 0;
-        preempt = 0;
-
-        /* Allocate a reference marker */
-        ipointer = (xfs_iptr_t *)kmem_zalloc(sizeof(xfs_iptr_t), KM_SLEEP);
+        xfs_perag_t     *pag = &mp->m_perag[ag];
+        boolean_t       vnode_refed = B_FALSE;
+        int             nr_found;
+        int             first_index = 0;
+        int             error = 0;
+        int             last_error = 0;
+        int             fflag = XFS_B_ASYNC;
+        int             lock_flags = XFS_ILOCK_SHARED;
 
-        fflag = XFS_B_ASYNC;            /* default is don't wait */
         if (flags & SYNC_DELWRI)
                 fflag = XFS_B_DELWRI;
         if (flags & SYNC_WAIT)
                 fflag = 0;              /* synchronous overrides all */
 
-        base_lock_flags = XFS_ILOCK_SHARED;
         if (flags & (SYNC_DELWRI | SYNC_CLOSE)) {
                 /*
                  * We need the I/O lock if we're going to call any of
                  * the flush/inval routines.
                  */
-                base_lock_flags |= XFS_IOLOCK_SHARED;
+                lock_flags |= XFS_IOLOCK_SHARED;
         }
 
-        XFS_MOUNT_ILOCK(mp);
-
-        ip = mp->m_inodes;
-
-        mount_locked = B_TRUE;
-        vnode_refed  = B_FALSE;
-
-        IPOINTER_CLR;
-
         do {
-                ASSERT(ipointer_in == B_FALSE);
-                ASSERT(vnode_refed == B_FALSE);
-
-                lock_flags = base_lock_flags;
-
                 /*
-                 * There were no inodes in the list, just break out
-                 * of the loop.
+                 * use a gang lookup to find the next inode in the tree
+                 * as the tree is sparse and a gang lookup walks to find
+                 * the number of objects requested.
                  */
-                if (ip == NULL) {
-                        break;
-                }
+                read_lock(&pag->pag_ici_lock);
+                nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
+                                (void**)&ip, first_index, 1);
 
-                /*
-                 * We found another sync thread marker - skip it
-                 */
-                if (ip->i_mount == NULL) {
-                        ip = ip->i_mnext;
-                        continue;
+                if (!nr_found) {
+                        read_unlock(&pag->pag_ici_lock);
+                        break;
                 }
 
-                vp = VFS_I(ip);
+                /* update the index for the next lookup */
+                first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
 
                 /*
-                 * If the vnode is gone then this is being torn down,
-                 * call reclaim if it is flushed, else let regular flush
-                 * code deal with it later in the loop.
+                 * skip inodes in reclaim. Let xfs_syncsub do that for
+                 * us so we don't need to worry.
                  */
-
-                if (vp == NULL) {
-                        /* Skip ones already in reclaim */
-                        if (ip->i_flags & XFS_IRECLAIM) {
-                                ip = ip->i_mnext;
-                                continue;
-                        }
-                        if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL) == 0) {
-                                ip = ip->i_mnext;
-                        } else if ((xfs_ipincount(ip) == 0) &&
-                                    xfs_iflock_nowait(ip)) {
-                                IPOINTER_INSERT(ip, mp);
-
-                                xfs_finish_reclaim(ip, 1,
-                                                XFS_IFLUSH_DELWRI_ELSE_ASYNC);
-
-                                XFS_MOUNT_ILOCK(mp);
-                                mount_locked = B_TRUE;
-                                IPOINTER_REMOVE(ip, mp);
-                        } else {
-                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
-                                ip = ip->i_mnext;
-                        }
+                vp = VFS_I(ip);
+                if (!vp) {
+                        read_unlock(&pag->pag_ici_lock);
                         continue;
                 }
 
+                /* bad inodes are dealt with elsewhere */
                 if (VN_BAD(vp)) {
-                        ip = ip->i_mnext;
+                        read_unlock(&pag->pag_ici_lock);
                         continue;
                 }
 
+                /* nothing to sync during shutdown */
                 if (XFS_FORCED_SHUTDOWN(mp) && !(flags & SYNC_CLOSE)) {
-                        XFS_MOUNT_IUNLOCK(mp);
-                        kmem_free(ipointer);
+                        read_unlock(&pag->pag_ici_lock);
                         return 0;
                 }
 
                 /*
-                 * Try to lock without sleeping.  We're out of order with
-                 * the inode list lock here, so if we fail we need to drop
-                 * the mount lock and try again.  If we're called from
-                 * bdflush() here, then don't bother.
-                 *
-                 * 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.
+                 * 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 (xfs_ilock_nowait(ip, lock_flags) == 0) {
-                        if (vp == NULL) {
-                                ip = ip->i_mnext;
-                                continue;
-                        }
-
                         vp = vn_grab(vp);
-                        if (vp == NULL) {
-                                ip = ip->i_mnext;
+                        read_unlock(&pag->pag_ici_lock);
+                        if (!vp)
                                 continue;
-                        }
-
-                        IPOINTER_INSERT(ip, mp);
                         xfs_ilock(ip, lock_flags);
 
                         ASSERT(vp == VFS_I(ip));
                         ASSERT(ip->i_mount == mp);
 
                         vnode_refed = B_TRUE;
+                } else {
+                        /* safe to unlock here as we have a reference */
+                        read_unlock(&pag->pag_ici_lock);
                 }
-
-                /* From here on in the loop we may have a marker record
-                 * in the inode list.
-                 */
-
                 /*
                  * If we have to flush data or wait for I/O completion
                  * we need to drop the ilock that we currently hold.
                  * If we need to drop the lock, insert a marker if we
                  * have not already done so.
                  */
-                if ((flags & (SYNC_CLOSE|SYNC_IOWAIT)) ||
-                    ((flags & SYNC_DELWRI) && VN_DIRTY(vp))) {
-                        if (mount_locked) {
-                                IPOINTER_INSERT(ip, mp);
-                        }
+                if (flags & SYNC_CLOSE) {
                         xfs_iunlock(ip, XFS_ILOCK_SHARED);
-
-                        if (flags & SYNC_CLOSE) {
-                                /* Shutdown case. Flush and invalidate. */
-                                if (XFS_FORCED_SHUTDOWN(mp))
-                                        xfs_tosspages(ip, 0, -1,
-                                                             FI_REMAPF);
-                                else
-                                        error = xfs_flushinval_pages(ip,
-                                                        0, -1, FI_REMAPF);
-                        } else if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
-                                error = xfs_flush_pages(ip, 0,
-                                                        -1, fflag, FI_NONE);
-                        }
-
-                        /*
-                         * When freezing, we need to wait ensure all I/O (including direct
-                         * I/O) is complete to ensure no further data modification can take
-                         * place after this point
-                         */
+                        if (XFS_FORCED_SHUTDOWN(mp))
+                                xfs_tosspages(ip, 0, -1, FI_REMAPF);
+                        else
+                                error = xfs_flushinval_pages(ip, 0, -1,
+                                                        FI_REMAPF);
+                        /* wait for I/O on freeze */
                         if (flags & SYNC_IOWAIT)
                                 vn_iowait(ip);
 
                         xfs_ilock(ip, XFS_ILOCK_SHARED);
                 }
 
-                if ((flags & SYNC_ATTR) &&
-                    (ip->i_update_core ||
-                     (ip->i_itemp && ip->i_itemp->ili_format.ilf_fields))) {
-                        if (mount_locked)
-                                IPOINTER_INSERT(ip, mp);
+                if ((flags & SYNC_DELWRI) && VN_DIRTY(vp)) {
+                        xfs_iunlock(ip, XFS_ILOCK_SHARED);
+                        error = xfs_flush_pages(ip, 0, -1, fflag, FI_NONE);
+                        if (flags & SYNC_IOWAIT)
+                                vn_iowait(ip);
+                        xfs_ilock(ip, XFS_ILOCK_SHARED);
+                }
 
+                if ((flags & SYNC_ATTR) && !xfs_inode_clean(ip)) {
                         if (flags & SYNC_WAIT) {
                                 xfs_iflock(ip);
-                                error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
-
-                        /*
-                         * If we can't acquire the flush lock, then the inode
-                         * is already being flushed so don't bother waiting.
-                         *
-                         * If we can lock it then do a delwri flush so we can
-                         * combine multiple inode flushes in each disk write.
-                         */
+                                if (!xfs_inode_clean(ip))
+                                        error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
+                                else
+                                        xfs_ifunlock(ip);
                         } else if (xfs_iflock_nowait(ip)) {
-                                error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
+                                if (!xfs_inode_clean(ip))
+                                        error = xfs_iflush(ip, XFS_IFLUSH_DELWRI);
+                                else
+                                        xfs_ifunlock(ip);
                         } else if (bypassed) {
                                 (*bypassed)++;
                         }
                 }
 
-                if (lock_flags != 0) {
+                if (lock_flags)
                         xfs_iunlock(ip, lock_flags);
-                }
 
                 if (vnode_refed) {
-                        /*
-                         * If we had to take a reference on the vnode
-                         * above, then wait until after we've unlocked
-                         * the inode to release the reference.  This is
-                         * because we can be already holding the inode
-                         * lock when IRELE() calls xfs_inactive().
-                         *
-                         * Make sure to drop the mount lock before calling
-                         * IRELE() so that we don't trip over ourselves if
-                         * we have to go for the mount lock again in the
-                         * inactive code.
-                         */
-                        if (mount_locked) {
-                                IPOINTER_INSERT(ip, mp);
-                        }
-
                         IRELE(ip);
-
                         vnode_refed = B_FALSE;
                 }
 
-                if (error) {
+                if (error)
                         last_error = error;
-                }
-
                 /*
                  * bail out if the filesystem is corrupted.
                  */
-                if (error == EFSCORRUPTED)  {
-                        if (!mount_locked) {
-                                XFS_MOUNT_ILOCK(mp);
-                                IPOINTER_REMOVE(ip, mp);
-                        }
-                        XFS_MOUNT_IUNLOCK(mp);
-                        ASSERT(ipointer_in == B_FALSE);
-                        kmem_free(ipointer);
+                if (error == EFSCORRUPTED)
                         return XFS_ERROR(error);
-                }
-
-                /* Let other threads have a chance at the mount lock
-                 * if we have looped many times without dropping the
-                 * lock.
-                 */
-                if ((++preempt & XFS_PREEMPT_MASK) == 0) {
-                        if (mount_locked) {
-                                IPOINTER_INSERT(ip, mp);
-                        }
-                }
-
-                if (mount_locked == B_FALSE) {
-                        XFS_MOUNT_ILOCK(mp);
-                        mount_locked = B_TRUE;
-                        IPOINTER_REMOVE(ip, mp);
-                        continue;
-                }
 
-                ASSERT(ipointer_in == B_FALSE);
-                ip = ip->i_mnext;
+        } while (nr_found);
 
-        } while (ip != mp->m_inodes);
+        return last_error;
+}
 
-        XFS_MOUNT_IUNLOCK(mp);
+int
+xfs_sync_inodes(
+        xfs_mount_t     *mp,
+        int             flags,
+        int             *bypassed)
+{
+        int             error;
+        int             last_error;
+        int             i;
 
-        ASSERT(ipointer_in == B_FALSE);
+        if (bypassed)
+                *bypassed = 0;
+        if (mp->m_flags & XFS_MOUNT_RDONLY)
+                return 0;
+        error = 0;
+        last_error = 0;
 
-        kmem_free(ipointer);
+        for (i = 0; i < mp->m_sb.sb_agcount; i++) {
+                if (!mp->m_perag[i].pag_ici_init)
+                        continue;
+                error = xfs_sync_inodes_ag(mp, i, flags, bypassed);
+                if (error)
+                        last_error = error;
+                if (error == EFSCORRUPTED)
+                        break;
+        }
         return XFS_ERROR(last_error);
 }