GFS2: stuck in inode wait, no glocks stuck

This patch changes the lock ordering when gfs2 reclaims
unlinked dinodes, thereby avoiding a livelock.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 3739155..8bce73e 100644 (file)
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -952,16 +952,14 @@ static int try_rgrp_fit(struct gfs2_rgrpd *rgd, struct gfs2_alloc *al)
  *          The inode, if one has been found, in inode.
  */
 
-static int try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
-                          u64 skip, struct inode **inode)
+static u64 try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
+                          u64 skip)
 {
        u32 goal = 0, block;
        u64 no_addr;
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        unsigned int n;
-       int error = 0;
 
-       *inode = NULL;
        for(;;) {
                if (goal >= rgd->rd_data)
                        break;
@@ -981,10 +979,7 @@ static int try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
                if (no_addr == skip)
                        continue;
                *last_unlinked = no_addr;
-               error = gfs2_unlinked_inode_lookup(rgd->rd_sbd->sd_vfs,
-                                                  no_addr, inode);
-               if (*inode || error)
-                       return error;
+               return no_addr;
        }
 
        rgd->rd_flags &= ~GFS2_RDF_CHECK;
@@ -1069,11 +1064,12 @@ static void forward_rgrp_set(struct gfs2_sbd *sdp, struct gfs2_rgrpd *rgd)
  * Try to acquire rgrp in way which avoids contending with others.
  *
  * Returns: errno
+ *          unlinked: the block address of an unlinked block to be reclaimed
  */
 
-static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
+static int get_local_rgrp(struct gfs2_inode *ip, u64 *unlinked,
+                         u64 *last_unlinked)
 {
-       struct inode *inode = NULL;
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_rgrpd *rgd, *begin = NULL;
        struct gfs2_alloc *al = ip->i_alloc;
@@ -1082,6 +1078,7 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
        int loops = 0;
        int error, rg_locked;
 
+       *unlinked = 0;
        rgd = gfs2_blk2rgrpd(sdp, ip->i_goal);
 
        while (rgd) {
@@ -1103,29 +1100,19 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
                           because that would require an iput which can only
                           happen after the rgrp is unlocked. */
                        if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
-                               error = try_rgrp_unlink(rgd, last_unlinked,
-                                                       ip->i_no_addr, &inode);
+                               *unlinked = try_rgrp_unlink(rgd, last_unlinked,
+                                                          ip->i_no_addr);
                        if (!rg_locked)
                                gfs2_glock_dq_uninit(&al->al_rgd_gh);
-                       if (inode) {
-                               if (error) {
-                                       if (inode->i_state & I_NEW)
-                                               iget_failed(inode);
-                                       else
-                                               iput(inode);
-                                       return ERR_PTR(error);
-                               }
-                               return inode;
-                       }
-                       if (error)
-                               return ERR_PTR(error);
+                       if (*unlinked)
+                               return -EAGAIN;
                        /* fall through */
                case GLR_TRYFAILED:
                        rgd = recent_rgrp_next(rgd);
                        break;
 
                default:
-                       return ERR_PTR(error);
+                       return error;
                }
        }
 
@@ -1148,22 +1135,12 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
                        if (try_rgrp_fit(rgd, al))
                                goto out;
                        if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
-                               error = try_rgrp_unlink(rgd, last_unlinked,
-                                                       ip->i_no_addr, &inode);
+                               *unlinked = try_rgrp_unlink(rgd, last_unlinked,
+                                                           ip->i_no_addr);
                        if (!rg_locked)
                                gfs2_glock_dq_uninit(&al->al_rgd_gh);
-                       if (inode) {
-                               if (error) {
-                                       if (inode->i_state & I_NEW)
-                                               iget_failed(inode);
-                                       else
-                                               iput(inode);
-                                       return ERR_PTR(error);
-                               }
-                               return inode;
-                       }
-                       if (error)
-                               return ERR_PTR(error);
+                       if (*unlinked)
+                               return -EAGAIN;
                        break;
 
                case GLR_TRYFAILED:
@@ -1171,7 +1148,7 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
                        break;
 
                default:
-                       return ERR_PTR(error);
+                       return error;
                }
 
                rgd = gfs2_rgrpd_get_next(rgd);
@@ -1180,7 +1157,7 @@ static struct inode *get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
 
                if (rgd == begin) {
                        if (++loops >= 3)
-                               return ERR_PTR(-ENOSPC);
+                               return -ENOSPC;
                        if (!skipped)
                                loops++;
                        flags = 0;
@@ -1200,7 +1177,7 @@ out:
                forward_rgrp_set(sdp, rgd);
        }
 
-       return NULL;
+       return 0;
 }
 
 /**
@@ -1216,7 +1193,7 @@ int gfs2_inplace_reserve_i(struct gfs2_inode *ip, char *file, unsigned int line)
        struct gfs2_alloc *al = ip->i_alloc;
        struct inode *inode;
        int error = 0;
-       u64 last_unlinked = NO_BLOCK;
+       u64 last_unlinked = NO_BLOCK, unlinked;
 
        if (gfs2_assert_warn(sdp, al->al_requested))
                return -EINVAL;
@@ -1232,14 +1209,19 @@ try_again:
        if (error)
                return error;
 
-       inode = get_local_rgrp(ip, &last_unlinked);
-       if (inode) {
+       error = get_local_rgrp(ip, &unlinked, &last_unlinked);
+       if (error) {
                if (ip != GFS2_I(sdp->sd_rindex))
                        gfs2_glock_dq_uninit(&al->al_ri_gh);
-               if (IS_ERR(inode))
-                       return PTR_ERR(inode);
-               iput(inode);
+               if (error != -EAGAIN)
+                       return error;
+               error = gfs2_unlinked_inode_lookup(ip->i_inode.i_sb,
+                                                  unlinked, &inode);
+               if (inode)
+                       iput(inode);
                gfs2_log_flush(sdp, NULL);
+               if (error == GLR_TRYFAILED)
+                       error = 0;
                goto try_again;
        }