GFS2: Extend the life of the reservations

This patch lengthens the lifespan of the reservations structure for
inodes. Before, they were allocated and deallocated for every write
operation. With this patch, they are allocated when the first write
occurs, and deallocated when the last process closes the file.
It's more efficient to do it this way because it saves GFS2 a lot of
unnecessary allocates and frees. It also gives us more flexibility
for the future: (1) we can now fold the qadata structure back into
the structure and save those alloc/frees, (2) we can use this for
multi-block reservations.

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

fs/gfs2/aops.c

@@ -878,7 +878,7 @@ static int gfs2_write_end(struct file *file, struct address_space *mapping,
 	brelse(dibh);
 failed:
 	gfs2_trans_end(sdp);
-	if (ip->i_res)
+	if (gfs2_mb_reserved(ip))
 		gfs2_inplace_release(ip);
 	if (qa) {
 		gfs2_quota_unlock(ip);

fs/gfs2/file.c

@@ -376,6 +376,10 @@ static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 	 */
 	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 
+	ret = gfs2_rs_alloc(ip);
+	if (ret)
+		return ret;
+
 	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
 	ret = gfs2_glock_nq(&gh);
 	if (ret)
@@ -569,10 +573,15 @@ static int gfs2_release(struct inode *inode, struct file *file)
 {
 	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 	struct gfs2_file *fp;
+	struct gfs2_inode *ip = GFS2_I(inode);
 
 	fp = file->private_data;
 	file->private_data = NULL;
 
+	if ((file->f_mode & FMODE_WRITE) && ip->i_res &&
+	    (atomic_read(&inode->i_writecount) == 1))
+		gfs2_rs_delete(ip);
+
 	if (gfs2_assert_warn(sdp, fp))
 		return -EIO;
 
@@ -653,12 +662,16 @@ static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 				   unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
+	struct dentry *dentry = file->f_dentry;
+	struct gfs2_inode *ip = GFS2_I(dentry->d_inode);
+	int ret;
+
+	ret = gfs2_rs_alloc(ip);
+	if (ret)
+		return ret;
 
 	if (file->f_flags & O_APPEND) {
-		struct dentry *dentry = file->f_dentry;
-		struct gfs2_inode *ip = GFS2_I(dentry->d_inode);
 		struct gfs2_holder gh;
-		int ret;
 
 		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 		if (ret)
@@ -774,6 +787,10 @@ static long gfs2_fallocate(struct file *file, int mode, loff_t offset,
 	if (bytes == 0)
 		bytes = sdp->sd_sb.sb_bsize;
 
+	error = gfs2_rs_alloc(ip);
+	if (error)
+		return error;
+
 	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 	error = gfs2_glock_nq(&ip->i_gh);
 	if (unlikely(error))

fs/gfs2/inode.c

@@ -667,6 +667,10 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (!name->len || name->len > GFS2_FNAMESIZE)
 		return -ENAMETOOLONG;
 
+	error = gfs2_rs_alloc(dip);
+	if (error)
+		return error;
+
 	error = gfs2_glock_nq_init(dip->i_gl, LM_ST_EXCLUSIVE, 0, ghs);
 	if (error)
 		goto fail;
@@ -704,6 +708,11 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (error)
 		goto fail_gunlock2;
 
+	/* the new inode needs a reservation so it can allocate xattrs. */
+	error = gfs2_rs_alloc(GFS2_I(inode));
+	if (error)
+		goto fail_gunlock2;
+
 	error = gfs2_acl_create(dip, inode);
 	if (error)
 		goto fail_gunlock2;
@@ -722,7 +731,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	gfs2_trans_end(sdp);
 	/* Check if we reserved space in the rgrp. Function link_dinode may
 	   not, depending on whether alloc is required. */
-	if (dip->i_res)
+	if (gfs2_mb_reserved(dip))
 		gfs2_inplace_release(dip);
 	gfs2_quota_unlock(dip);
 	gfs2_qadata_put(dip);
@@ -819,6 +828,10 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir,
 	if (S_ISDIR(inode->i_mode))
 		return -EPERM;
 
+	error = gfs2_rs_alloc(dip);
+	if (error)
+		return error;
+
 	gfs2_holder_init(dip->i_gl, LM_ST_EXCLUSIVE, 0, ghs);
 	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, ghs + 1);
 
@@ -1234,6 +1247,10 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 	if (error)
 		return error;
 
+	error = gfs2_rs_alloc(ndip);
+	if (error)
+		return error;
+
 	if (odip != ndip) {
 		error = gfs2_glock_nq_init(sdp->sd_rename_gl, LM_ST_EXCLUSIVE,
 					   0, &r_gh);
@@ -1644,6 +1661,10 @@ static int gfs2_setattr(struct dentry *dentry, struct iattr *attr)
 	struct gfs2_holder i_gh;
 	int error;
 
+	error = gfs2_rs_alloc(ip);
+	if (error)
+		return error;
+
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
 	if (error)
 		return error;

fs/gfs2/quota.c

@@ -764,6 +764,10 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
 	unsigned int nalloc = 0, blocks;
 	int error;
 
+	error = gfs2_rs_alloc(ip);
+	if (error)
+		return error;
+
 	gfs2_write_calc_reserv(ip, sizeof(struct gfs2_quota),
 			      &data_blocks, &ind_blocks);
 
@@ -1549,10 +1553,14 @@ static int gfs2_set_dqblk(struct super_block *sb, int type, qid_t id,
 	if (error)
 		return error;
 
+	error = gfs2_rs_alloc(ip);
+	if (error)
+		goto out_put;
+
 	mutex_lock(&ip->i_inode.i_mutex);
 	error = gfs2_glock_nq_init(qd->qd_gl, LM_ST_EXCLUSIVE, 0, &q_gh);
 	if (error)
-		goto out_put;
+		goto out_unlockput;
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
 	if (error)
 		goto out_q;
@@ -1609,8 +1617,9 @@ out_i:
 	gfs2_glock_dq_uninit(&i_gh);
 out_q:
 	gfs2_glock_dq_uninit(&q_gh);
-out_put:
+out_unlockput:
 	mutex_unlock(&ip->i_inode.i_mutex);
+out_put:
 	qd_put(qd);
 	return error;
 }

fs/gfs2/rgrp.c

@@ -417,6 +417,39 @@ void gfs2_free_clones(struct gfs2_rgrpd *rgd)
 	}
 }
 
+/**
+ * gfs2_rs_alloc - make sure we have a reservation assigned to the inode
+ * @ip: the inode for this reservation
+ */
+int gfs2_rs_alloc(struct gfs2_inode *ip)
+{
+	int error = 0;
+
+	down_write(&ip->i_rw_mutex);
+	if (!ip->i_res) {
+		ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
+		if (!ip->i_res)
+			error = -ENOMEM;
+	}
+	up_write(&ip->i_rw_mutex);
+	return error;
+}
+
+/**
+ * gfs2_rs_delete - delete a reservation
+ * @ip: The inode for this reservation
+ *
+ */
+void gfs2_rs_delete(struct gfs2_inode *ip)
+{
+	down_write(&ip->i_rw_mutex);
+	if (ip->i_res) {
+		kmem_cache_free(gfs2_rsrv_cachep, ip->i_res);
+		ip->i_res = NULL;
+	}
+	up_write(&ip->i_rw_mutex);
+}
+
 void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
 {
 	struct rb_node *n;
@@ -992,22 +1025,6 @@ struct gfs2_qadata *gfs2_qadata_get(struct gfs2_inode *ip)
 	return ip->i_qadata;
 }
 
-/**
- * gfs2_blkrsv_get - get the struct gfs2_blkreserv structure for an inode
- * @ip: the incore GFS2 inode structure
- *
- * Returns: the struct gfs2_qadata
- */
-
-static int gfs2_blkrsv_get(struct gfs2_inode *ip)
-{
-	BUG_ON(ip->i_res != NULL);
-	ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
-	if (!ip->i_res)
-		return -ENOMEM;
-	return 0;
-}
-
 /**
  * try_rgrp_fit - See if a given reservation will fit in a given RG
  * @rgd: the RG data
@@ -1162,13 +1179,6 @@ static int get_local_rgrp(struct gfs2_inode *ip, u64 *last_unlinked)
 	return -ENOSPC;
 }
 
-static void gfs2_blkrsv_put(struct gfs2_inode *ip)
-{
-	BUG_ON(ip->i_res == NULL);
-	kmem_cache_free(gfs2_rsrv_cachep, ip->i_res);
-	ip->i_res = NULL;
-}
-
 /**
  * gfs2_inplace_reserve - Reserve space in the filesystem
  * @ip: the inode to reserve space for
@@ -1181,14 +1191,10 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 {
 	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
 	struct gfs2_blkreserv *rs;
-	int error;
+	int error = 0;
 	u64 last_unlinked = NO_BLOCK;
 	int tries = 0;
 
-	error = gfs2_blkrsv_get(ip);
-	if (error)
-		return error;
-
 	rs = ip->i_res;
 	rs->rs_requested = requested;
 	if (gfs2_assert_warn(sdp, requested)) {
@@ -1213,7 +1219,7 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
 
 out:
 	if (error)
-		gfs2_blkrsv_put(ip);
+		rs->rs_requested = 0;
 	return error;
 }
 
@@ -1230,7 +1236,7 @@ void gfs2_inplace_release(struct gfs2_inode *ip)
 
 	if (rs->rs_rgd_gh.gh_gl)
 		gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
-	gfs2_blkrsv_put(ip);
+	rs->rs_requested = 0;
 }
 
 /**
@@ -1496,7 +1502,7 @@ int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,
 	/* Only happens if there is a bug in gfs2, return something distinctive
 	 * to ensure that it is noticed.
 	 */
-	if (ip->i_res == NULL)
+	if (ip->i_res->rs_requested == 0)
 		return -ECANCELED;
 
 	rgd = ip->i_rgd;

fs/gfs2/rgrp.h

@@ -43,6 +43,8 @@ extern void gfs2_inplace_release(struct gfs2_inode *ip);
 extern int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *n,
 			     bool dinode, u64 *generation);
 
+extern int gfs2_rs_alloc(struct gfs2_inode *ip);
+extern void gfs2_rs_delete(struct gfs2_inode *ip);
 extern void __gfs2_free_blocks(struct gfs2_inode *ip, u64 bstart, u32 blen, int meta);
 extern void gfs2_free_meta(struct gfs2_inode *ip, u64 bstart, u32 blen);
 extern void gfs2_free_di(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip);
@@ -68,4 +70,12 @@ extern int gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 				   const struct gfs2_bitmap *bi, unsigned minlen, u64 *ptrimmed);
 extern int gfs2_fitrim(struct file *filp, void __user *argp);
 
+/* This is how to tell if a reservation is "inplace" reserved: */
+static inline int gfs2_mb_reserved(struct gfs2_inode *ip)
+{
+	if (ip->i_res && ip->i_res->rs_requested)
+		return 1;
+	return 0;
+}
+
 #endif /* __RGRP_DOT_H__ */

fs/gfs2/super.c

@@ -1554,6 +1554,7 @@ out_unlock:
 out:
 	/* Case 3 starts here */
 	truncate_inode_pages(&inode->i_data, 0);
+	gfs2_rs_delete(ip);
 	clear_inode(inode);
 	gfs2_dir_hash_inval(ip);
 	ip->i_gl->gl_object = NULL;
@@ -1576,6 +1577,7 @@ static struct inode *gfs2_alloc_inode(struct super_block *sb)
 		ip->i_flags = 0;
 		ip->i_gl = NULL;
 		ip->i_rgd = NULL;
+		ip->i_res = NULL;
 	}
 	return &ip->i_inode;
 }

fs/gfs2/trans.h

@@ -31,7 +31,7 @@ struct gfs2_glock;
 static inline unsigned int gfs2_rg_blocks(const struct gfs2_inode *ip)
 {
 	const struct gfs2_blkreserv *rs = ip->i_res;
-	if (rs->rs_requested < ip->i_rgd->rd_length)
+	if (rs && rs->rs_requested < ip->i_rgd->rd_length)
 		return rs->rs_requested + 1;
 	return ip->i_rgd->rd_length;
 }