GFS2: Reduce file fragmentation

This patch reduces GFS2 file fragmentation by pre-reserving blocks. The
resulting improved on disk layout greatly speeds up operations in cases
which would have resulted in interlaced allocation of blocks previously.
A typical example of this is 10 parallel dd processes, each writing to a
file in a common dirctory.

The implementation uses an rbtree of reservations attached to each
resource group (and each inode).

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

1 files changed, 11 insertions, 13 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 6fbf3cbd974d..9f94832cefec 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -383,6 +383,9 @@ static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
         if (ret)
                 return ret;
 
+        atomic_set(&ip->i_res->rs_sizehint,
+                   PAGE_CACHE_SIZE / sdp->sd_sb.sb_bsize);
+
         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
         ret = gfs2_glock_nq(&gh);
         if (ret)
@@ -571,22 +574,15 @@ fail:
 
 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;
+        kfree(file->private_data);
         file->private_data = NULL;
 
-        if ((file->f_mode & FMODE_WRITE) && ip->i_res &&
+        if ((file->f_mode & FMODE_WRITE) &&
             (atomic_read(&inode->i_writecount) == 1))
                 gfs2_rs_delete(ip);
 
-        if (gfs2_assert_warn(sdp, fp))
-                return -EIO;
-
-        kfree(fp);
-
         return 0;
 }
 
@@ -662,14 +658,18 @@ 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;
+        size_t writesize = iov_length(iov, nr_segs);
         struct dentry *dentry = file->f_dentry;
         struct gfs2_inode *ip = GFS2_I(dentry->d_inode);
+        struct gfs2_sbd *sdp;
         int ret;
 
+        sdp = GFS2_SB(file->f_mapping->host);
         ret = gfs2_rs_alloc(ip);
         if (ret)
                 return ret;
 
+        atomic_set(&ip->i_res->rs_sizehint, writesize / sdp->sd_sb.sb_bsize);
         if (file->f_flags & O_APPEND) {
                 struct gfs2_holder gh;
 
@@ -795,6 +795,8 @@ static long gfs2_fallocate(struct file *file, int mode, loff_t offset,
         if (unlikely(error))
                 goto out_uninit;
 
+        atomic_set(&ip->i_res->rs_sizehint, len / sdp->sd_sb.sb_bsize);
+
         while (len > 0) {
                 if (len < bytes)
                         bytes = len;
@@ -803,10 +805,6 @@ static long gfs2_fallocate(struct file *file, int mode, loff_t offset,
                         offset += bytes;
                         continue;
                 }
-                error = gfs2_rindex_update(sdp);
-                if (error)
-                        goto out_unlock;
-
                 error = gfs2_quota_lock_check(ip);
                 if (error)
                         goto out_unlock;