Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes

* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes:
  GFS2: Fix inode deallocation race

5 files changed, 98 insertions, 216 deletions

diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index 06d582732d34..5ab3839dfcb9 100644
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -138,10 +138,8 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb,
 				      struct gfs2_inum_host *inum)
 {
 	struct gfs2_sbd *sdp = sb->s_fs_info;
-	struct gfs2_holder i_gh;
 	struct inode *inode;
 	struct dentry *dentry;
-	int error;
 
 	inode = gfs2_ilookup(sb, inum->no_addr);
 	if (inode) {
@@ -152,52 +150,16 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb,
 		goto out_inode;
 	}
 
-	error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
-				  LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
-	if (error)
-		return ERR_PTR(error);
-
-	error = gfs2_check_blk_type(sdp, inum->no_addr, GFS2_BLKST_DINODE);
-	if (error)
-		goto fail;
-
-	inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0);
-	if (IS_ERR(inode)) {
-		error = PTR_ERR(inode);
-		goto fail;
-	}
-
-	error = gfs2_inode_refresh(GFS2_I(inode));
-	if (error) {
-		iput(inode);
-		goto fail;
-	}
-
-	/* Pick up the works we bypass in gfs2_inode_lookup */
-	if (inode->i_state & I_NEW) 
-		gfs2_set_iop(inode);
-
-	if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
-		iput(inode);
-		goto fail;
-	}
-
-	error = -EIO;
-	if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM) {
-		iput(inode);
-		goto fail;
-	}
-
-	gfs2_glock_dq_uninit(&i_gh);
+	inode = gfs2_lookup_by_inum(sdp, inum->no_addr, &inum->no_formal_ino,
+				    GFS2_BLKST_DINODE);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
 
 out_inode:
 	dentry = d_obtain_alias(inode);
 	if (!IS_ERR(dentry))
 		dentry->d_op = &gfs2_dops;
 	return dentry;
-fail:
-	gfs2_glock_dq_uninit(&i_gh);
-	return ERR_PTR(error);
 }
 
 static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 87778857f099..f92c17704169 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -686,21 +686,20 @@ static void delete_work_func(struct work_struct *work)
 {
 	struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 	struct gfs2_sbd *sdp = gl->gl_sbd;
-	struct gfs2_inode *ip = NULL;
+	struct gfs2_inode *ip;
 	struct inode *inode;
-	u64 no_addr = 0;
+	u64 no_addr = gl->gl_name.ln_number;
+
+	ip = gl->gl_object;
+	/* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 
-	spin_lock(&gl->gl_spin);
-	ip = (struct gfs2_inode *)gl->gl_object;
 	if (ip)
-		no_addr = ip->i_no_addr;
-	spin_unlock(&gl->gl_spin);
-	if (ip) {
 		inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
-		if (inode) {
-			d_prune_aliases(inode);
-			iput(inode);
-		}
+	else
+		inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
+	if (inode && !IS_ERR(inode)) {
+		d_prune_aliases(inode);
+		iput(inode);
 	}
 	gfs2_glock_put(gl);
 }
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 06370f8bd8cf..e1213f7f9217 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -73,49 +73,6 @@ static struct inode *gfs2_iget(struct super_block *sb, u64 no_addr)
 	return iget5_locked(sb, hash, iget_test, iget_set, &no_addr);
 }
 
-struct gfs2_skip_data {
-	u64	no_addr;
-	int	skipped;
-};
-
-static int iget_skip_test(struct inode *inode, void *opaque)
-{
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_skip_data *data = opaque;
-
-	if (ip->i_no_addr == data->no_addr) {
-		if (inode->i_state & (I_FREEING|I_WILL_FREE)){
-			data->skipped = 1;
-			return 0;
-		}
-		return 1;
-	}
-	return 0;
-}
-
-static int iget_skip_set(struct inode *inode, void *opaque)
-{
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_skip_data *data = opaque;
-
-	if (data->skipped)
-		return 1;
-	inode->i_ino = (unsigned long)(data->no_addr);
-	ip->i_no_addr = data->no_addr;
-	return 0;
-}
-
-static struct inode *gfs2_iget_skip(struct super_block *sb,
-				    u64 no_addr)
-{
-	struct gfs2_skip_data data;
-	unsigned long hash = (unsigned long)no_addr;
-
-	data.no_addr = no_addr;
-	data.skipped = 0;
-	return iget5_locked(sb, hash, iget_skip_test, iget_skip_set, &data);
-}
-
 /**
  * GFS2 lookup code fills in vfs inode contents based on info obtained
  * from directory entry inside gfs2_inode_lookup(). This has caused issues
@@ -243,93 +200,54 @@ fail:
 	return ERR_PTR(error);
 }
 
-/**
- * gfs2_process_unlinked_inode - Lookup an unlinked inode for reclamation
- *                               and try to reclaim it by doing iput.
- *
- * This function assumes no rgrp locks are currently held.
- *
- * @sb: The super block
- * no_addr: The inode number
- *
- */
-
-void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr)
+struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
+				  u64 *no_formal_ino, unsigned int blktype)
 {
-	struct gfs2_sbd *sdp;
-	struct gfs2_inode *ip;
-	struct gfs2_glock *io_gl = NULL;
-	int error;
-	struct gfs2_holder gh;
+	struct super_block *sb = sdp->sd_vfs;
+	struct gfs2_holder i_gh;
 	struct inode *inode;
+	int error;
 
-	inode = gfs2_iget_skip(sb, no_addr);
-
-	if (!inode)
-		return;
-
-	/* If it's not a new inode, someone's using it, so leave it alone. */
-	if (!(inode->i_state & I_NEW)) {
-		iput(inode);
-		return;
-	}
-
-	ip = GFS2_I(inode);
-	sdp = GFS2_SB(inode);
-	ip->i_no_formal_ino = -1;
+	error = gfs2_glock_nq_num(sdp, no_addr, &gfs2_inode_glops,
+				  LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
+	if (error)
+		return ERR_PTR(error);
 
-	error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
-	if (unlikely(error))
+	error = gfs2_check_blk_type(sdp, no_addr, blktype);
+	if (error)
 		goto fail;
-	ip->i_gl->gl_object = ip;
 
-	error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
-	if (unlikely(error))
-		goto fail_put;
-
-	set_bit(GIF_INVALID, &ip->i_flags);
-	error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, LM_FLAG_TRY | GL_EXACT,
-				   &ip->i_iopen_gh);
-	if (unlikely(error))
-		goto fail_iopen;
+	inode = gfs2_inode_lookup(sb, DT_UNKNOWN, no_addr, 0);
+	if (IS_ERR(inode))
+		goto fail;
 
-	ip->i_iopen_gh.gh_gl->gl_object = ip;
-	gfs2_glock_put(io_gl);
-	io_gl = NULL;
+	error = gfs2_inode_refresh(GFS2_I(inode));
+	if (error)
+		goto fail_iput;
 
-	inode->i_mode = DT2IF(DT_UNKNOWN);
+	/* Pick up the works we bypass in gfs2_inode_lookup */
+	if (inode->i_state & I_NEW) 
+		gfs2_set_iop(inode);
 
-	/*
-	 * We must read the inode in order to work out its type in
-	 * this case. Note that this doesn't happen often as we normally
-	 * know the type beforehand. This code path only occurs during
-	 * unlinked inode recovery (where it is safe to do this glock,
-	 * which is not true in the general case).
-	 */
-	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, LM_FLAG_TRY,
-				   &gh);
-	if (unlikely(error))
-		goto fail_glock;
+	/* Two extra checks for NFS only */
+	if (no_formal_ino) {
+		error = -ESTALE;
+		if (GFS2_I(inode)->i_no_formal_ino != *no_formal_ino)
+			goto fail_iput;
 
-	/* Inode is now uptodate */
-	gfs2_glock_dq_uninit(&gh);
-	gfs2_set_iop(inode);
+		error = -EIO;
+		if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM)
+			goto fail_iput;
 
-	/* The iput will cause it to be deleted. */
-	iput(inode);
-	return;
+		error = 0;
+	}
 
-fail_glock:
-	gfs2_glock_dq(&ip->i_iopen_gh);
-fail_iopen:
-	if (io_gl)
-		gfs2_glock_put(io_gl);
-fail_put:
-	ip->i_gl->gl_object = NULL;
-	gfs2_glock_put(ip->i_gl);
 fail:
-	iget_failed(inode);
-	return;
+	gfs2_glock_dq_uninit(&i_gh);
+	return error ? ERR_PTR(error) : inode;
+fail_iput:
+	iput(inode);
+	goto fail;
 }
 
 static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf)
diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index 6720d7d5fbc6..d8499fadcc53 100644
--- a/fs/gfs2/inode.h
+++ b/fs/gfs2/inode.h
@@ -99,7 +99,9 @@ err:
 extern void gfs2_set_iop(struct inode *inode);
 extern struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned type, 
 				       u64 no_addr, u64 no_formal_ino);
-extern void gfs2_process_unlinked_inode(struct super_block *sb, u64 no_addr);
+extern struct inode *gfs2_lookup_by_inum(struct gfs2_sbd *sdp, u64 no_addr,
+					 u64 *no_formal_ino,
+					 unsigned int blktype);
 extern struct inode *gfs2_ilookup(struct super_block *sb, u64 no_addr);
 
 extern int gfs2_inode_refresh(struct gfs2_inode *ip);
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index bef3ab6cf5c1..33c8407b876f 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -963,17 +963,18 @@ static int try_rgrp_fit(struct gfs2_rgrpd *rgd, struct gfs2_alloc *al)
  *          The inode, if one has been found, in inode.
  */
 
-static u64 try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
-			   u64 skip)
+static void 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;
+	struct gfs2_glock *gl;
+	struct gfs2_inode *ip;
+	int error;
+	int found = 0;
 
-	for(;;) {
-		if (goal >= rgd->rd_data)
-			break;
+	while (goal < rgd->rd_data) {
 		down_write(&sdp->sd_log_flush_lock);
 		n = 1;
 		block = rgblk_search(rgd, goal, GFS2_BLKST_UNLINKED,
@@ -990,11 +991,32 @@ static u64 try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked,
 		if (no_addr == skip)
 			continue;
 		*last_unlinked = no_addr;
-		return no_addr;
+
+		error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &gl);
+		if (error)
+			continue;
+
+		/* If the inode is already in cache, we can ignore it here
+		 * because the existing inode disposal code will deal with
+		 * it when all refs have gone away. Accessing gl_object like
+		 * this is not safe in general. Here it is ok because we do
+		 * not dereference the pointer, and we only need an approx
+		 * answer to whether it is NULL or not.
+		 */
+		ip = gl->gl_object;
+
+		if (ip || queue_work(gfs2_delete_workqueue, &gl->gl_delete) == 0)
+			gfs2_glock_put(gl);
+		else
+			found++;
+
+		/* Limit reclaim to sensible number of tasks */
+		if (found > 2*NR_CPUS)
+			return;
 	}
 
 	rgd->rd_flags &= ~GFS2_RDF_CHECK;
-	return 0;
+	return;
 }
 
 /**
@@ -1075,11 +1097,9 @@ 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 int get_local_rgrp(struct gfs2_inode *ip, u64 *unlinked,
-			  u64 *last_unlinked)
+static int get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct gfs2_rgrpd *rgd, *begin = NULL;
@@ -1089,7 +1109,6 @@ static int get_local_rgrp(struct gfs2_inode *ip, u64 *unlinked,
 	int loops = 0;
 	int error, rg_locked;
 
-	*unlinked = 0;
 	rgd = gfs2_blk2rgrpd(sdp, ip->i_goal);
 
 	while (rgd) {
@@ -1106,17 +1125,10 @@ static int get_local_rgrp(struct gfs2_inode *ip, u64 *unlinked,
 		case 0:
 			if (try_rgrp_fit(rgd, al))
 				goto out;
-			/* If the rg came in already locked, there's no
-			   way we can recover from a failed try_rgrp_unlink
-			   because that would require an iput which can only
-			   happen after the rgrp is unlocked. */
-			if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
-				*unlinked = try_rgrp_unlink(rgd, last_unlinked,
-							   ip->i_no_addr);
+			if (rgd->rd_flags & GFS2_RDF_CHECK)
+				try_rgrp_unlink(rgd, last_unlinked, ip->i_no_addr);
 			if (!rg_locked)
 				gfs2_glock_dq_uninit(&al->al_rgd_gh);
-			if (*unlinked)
-				return -EAGAIN;
 			/* fall through */
 		case GLR_TRYFAILED:
 			rgd = recent_rgrp_next(rgd);
@@ -1145,13 +1157,10 @@ static int get_local_rgrp(struct gfs2_inode *ip, u64 *unlinked,
 		case 0:
 			if (try_rgrp_fit(rgd, al))
 				goto out;
-			if (!rg_locked && rgd->rd_flags & GFS2_RDF_CHECK)
-				*unlinked = try_rgrp_unlink(rgd, last_unlinked,
-							    ip->i_no_addr);
+			if (rgd->rd_flags & GFS2_RDF_CHECK)
+				try_rgrp_unlink(rgd, last_unlinked, ip->i_no_addr);
 			if (!rg_locked)
 				gfs2_glock_dq_uninit(&al->al_rgd_gh);
-			if (*unlinked)
-				return -EAGAIN;
 			break;
 
 		case GLR_TRYFAILED:
@@ -1204,12 +1213,12 @@ int gfs2_inplace_reserve_i(struct gfs2_inode *ip, int hold_rindex,
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct gfs2_alloc *al = ip->i_alloc;
 	int error = 0;
-	u64 last_unlinked = NO_BLOCK, unlinked;
+	u64 last_unlinked = NO_BLOCK;
+	int tries = 0;
 
 	if (gfs2_assert_warn(sdp, al->al_requested))
 		return -EINVAL;
 
-try_again:
 	if (hold_rindex) {
 		/* We need to hold the rindex unless the inode we're using is
 		   the rindex itself, in which case it's already held. */
@@ -1218,31 +1227,23 @@ try_again:
 		else if (!sdp->sd_rgrps) /* We may not have the rindex read
 					    in, so: */
 			error = gfs2_ri_update_special(ip);
+		if (error)
+			return error;
 	}
 
-	if (error)
-		return error;
+	do {
+		error = get_local_rgrp(ip, &last_unlinked);
+		/* If there is no space, flushing the log may release some */
+		if (error)
+			gfs2_log_flush(sdp, NULL);
+	} while (error && tries++ < 3);
 
-	/* Find an rgrp suitable for allocation.  If it encounters any unlinked
-	   dinodes along the way, error will equal -EAGAIN and unlinked will
-	   contains it block address. We then need to look up that inode and
-	   try to free it, and try the allocation again. */
-	error = get_local_rgrp(ip, &unlinked, &last_unlinked);
 	if (error) {
 		if (hold_rindex && ip != GFS2_I(sdp->sd_rindex))
 			gfs2_glock_dq_uninit(&al->al_ri_gh);
-		if (error != -EAGAIN)
-			return error;
-
-		gfs2_process_unlinked_inode(ip->i_inode.i_sb, unlinked);
-		/* regardless of whether or not gfs2_process_unlinked_inode
-		   was successful, we don't want to repeat it again. */
-		last_unlinked = unlinked;
-		gfs2_log_flush(sdp, NULL);
-		error = 0;
-
-		goto try_again;
+		return error;
 	}
+
 	/* no error, so we have the rgrp set in the inode's allocation. */
 	al->al_file = file;
 	al->al_line = line;