ceph: optimize memory usage

In current code, regular file and directory use same struct
ceph_file_info to store fs specific data so the struct has to
include some fields which are only used for directory
(e.g., readdir related info), when having plenty of regular files,
it will lead to memory waste.

This patch introduces dedicated ceph_dir_file_info cache for
readdir related thins. So that regular file does not include those
unused fields anymore.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 94 insertions, 91 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 1aa3bfc9ef35..16405e0774a6 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -102,18 +102,18 @@ static int fpos_cmp(loff_t l, loff_t r)
  * regardless of what dir changes take place on the
  * server.
  */
-static int note_last_dentry(struct ceph_file_info *fi, const char *name,
+static int note_last_dentry(struct ceph_dir_file_info *dfi, const char *name,
 		            int len, unsigned next_offset)
 {
 	char *buf = kmalloc(len+1, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
-	kfree(fi->last_name);
-	fi->last_name = buf;
-	memcpy(fi->last_name, name, len);
-	fi->last_name[len] = 0;
-	fi->next_offset = next_offset;
-	dout("note_last_dentry '%s'\n", fi->last_name);
+	kfree(dfi->last_name);
+	dfi->last_name = buf;
+	memcpy(dfi->last_name, name, len);
+	dfi->last_name[len] = 0;
+	dfi->next_offset = next_offset;
+	dout("note_last_dentry '%s'\n", dfi->last_name);
 	return 0;
 }
 
@@ -175,7 +175,7 @@ __dcache_find_get_entry(struct dentry *parent, u64 idx,
 static int __dcache_readdir(struct file *file,  struct dir_context *ctx,
 			    int shared_gen)
 {
-	struct ceph_file_info *fi = file->private_data;
+	struct ceph_dir_file_info *dfi = file->private_data;
 	struct dentry *parent = file->f_path.dentry;
 	struct inode *dir = d_inode(parent);
 	struct dentry *dentry, *last = NULL;
@@ -222,7 +222,7 @@ static int __dcache_readdir(struct file *file,  struct dir_context *ctx,
 		bool emit_dentry = false;
 		dentry = __dcache_find_get_entry(parent, idx++, &cache_ctl);
 		if (!dentry) {
-			fi->flags |= CEPH_F_ATEND;
+			dfi->file_info.flags |= CEPH_F_ATEND;
 			err = 0;
 			break;
 		}
@@ -273,33 +273,33 @@ out:
 	if (last) {
 		int ret;
 		di = ceph_dentry(last);
-		ret = note_last_dentry(fi, last->d_name.name, last->d_name.len,
+		ret = note_last_dentry(dfi, last->d_name.name, last->d_name.len,
 				       fpos_off(di->offset) + 1);
 		if (ret < 0)
 			err = ret;
 		dput(last);
 		/* last_name no longer match cache index */
-		if (fi->readdir_cache_idx >= 0) {
-			fi->readdir_cache_idx = -1;
-			fi->dir_release_count = 0;
+		if (dfi->readdir_cache_idx >= 0) {
+			dfi->readdir_cache_idx = -1;
+			dfi->dir_release_count = 0;
 		}
 	}
 	return err;
 }
 
-static bool need_send_readdir(struct ceph_file_info *fi, loff_t pos)
+static bool need_send_readdir(struct ceph_dir_file_info *dfi, loff_t pos)
 {
-	if (!fi->last_readdir)
+	if (!dfi->last_readdir)
 		return true;
 	if (is_hash_order(pos))
-		return !ceph_frag_contains_value(fi->frag, fpos_hash(pos));
+		return !ceph_frag_contains_value(dfi->frag, fpos_hash(pos));
 	else
-		return fi->frag != fpos_frag(pos);
+		return dfi->frag != fpos_frag(pos);
 }
 
 static int ceph_readdir(struct file *file, struct dir_context *ctx)
 {
-	struct ceph_file_info *fi = file->private_data;
+	struct ceph_dir_file_info *dfi = file->private_data;
 	struct inode *inode = file_inode(file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
@@ -310,7 +310,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	struct ceph_mds_reply_info_parsed *rinfo;
 
 	dout("readdir %p file %p pos %llx\n", inode, file, ctx->pos);
-	if (fi->flags & CEPH_F_ATEND)
+	if (dfi->file_info.flags & CEPH_F_ATEND)
 		return 0;
 
 	/* always start with . and .. */
@@ -351,15 +351,15 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	/* proceed with a normal readdir */
 more:
 	/* do we have the correct frag content buffered? */
-	if (need_send_readdir(fi, ctx->pos)) {
+	if (need_send_readdir(dfi, ctx->pos)) {
 		struct ceph_mds_request *req;
 		int op = ceph_snap(inode) == CEPH_SNAPDIR ?
 			CEPH_MDS_OP_LSSNAP : CEPH_MDS_OP_READDIR;
 
 		/* discard old result, if any */
-		if (fi->last_readdir) {
-			ceph_mdsc_put_request(fi->last_readdir);
-			fi->last_readdir = NULL;
+		if (dfi->last_readdir) {
+			ceph_mdsc_put_request(dfi->last_readdir);
+			dfi->last_readdir = NULL;
 		}
 
 		if (is_hash_order(ctx->pos)) {
@@ -373,7 +373,7 @@ more:
 		}
 
 		dout("readdir fetching %llx.%llx frag %x offset '%s'\n",
-		     ceph_vinop(inode), frag, fi->last_name);
+		     ceph_vinop(inode), frag, dfi->last_name);
 		req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
 		if (IS_ERR(req))
 			return PTR_ERR(req);
@@ -389,8 +389,8 @@ more:
 			__set_bit(CEPH_MDS_R_DIRECT_IS_HASH, &req->r_req_flags);
 			req->r_inode_drop = CEPH_CAP_FILE_EXCL;
 		}
-		if (fi->last_name) {
-			req->r_path2 = kstrdup(fi->last_name, GFP_KERNEL);
+		if (dfi->last_name) {
+			req->r_path2 = kstrdup(dfi->last_name, GFP_KERNEL);
 			if (!req->r_path2) {
 				ceph_mdsc_put_request(req);
 				return -ENOMEM;
@@ -400,10 +400,10 @@ more:
 				cpu_to_le32(fpos_hash(ctx->pos));
 		}
 
-		req->r_dir_release_cnt = fi->dir_release_count;
-		req->r_dir_ordered_cnt = fi->dir_ordered_count;
-		req->r_readdir_cache_idx = fi->readdir_cache_idx;
-		req->r_readdir_offset = fi->next_offset;
+		req->r_dir_release_cnt = dfi->dir_release_count;
+		req->r_dir_ordered_cnt = dfi->dir_ordered_count;
+		req->r_readdir_cache_idx = dfi->readdir_cache_idx;
+		req->r_readdir_offset = dfi->next_offset;
 		req->r_args.readdir.frag = cpu_to_le32(frag);
 		req->r_args.readdir.flags =
 				cpu_to_le16(CEPH_READDIR_REPLY_BITFLAGS);
@@ -427,35 +427,35 @@ more:
 		if (le32_to_cpu(rinfo->dir_dir->frag) != frag) {
 			frag = le32_to_cpu(rinfo->dir_dir->frag);
 			if (!rinfo->hash_order) {
-				fi->next_offset = req->r_readdir_offset;
+				dfi->next_offset = req->r_readdir_offset;
 				/* adjust ctx->pos to beginning of frag */
 				ctx->pos = ceph_make_fpos(frag,
-							  fi->next_offset,
+							  dfi->next_offset,
 							  false);
 			}
 		}
 
-		fi->frag = frag;
-		fi->last_readdir = req;
+		dfi->frag = frag;
+		dfi->last_readdir = req;
 
 		if (test_bit(CEPH_MDS_R_DID_PREPOPULATE, &req->r_req_flags)) {
-			fi->readdir_cache_idx = req->r_readdir_cache_idx;
-			if (fi->readdir_cache_idx < 0) {
+			dfi->readdir_cache_idx = req->r_readdir_cache_idx;
+			if (dfi->readdir_cache_idx < 0) {
 				/* preclude from marking dir ordered */
-				fi->dir_ordered_count = 0;
+				dfi->dir_ordered_count = 0;
 			} else if (ceph_frag_is_leftmost(frag) &&
-				   fi->next_offset == 2) {
+				   dfi->next_offset == 2) {
 				/* note dir version at start of readdir so
 				 * we can tell if any dentries get dropped */
-				fi->dir_release_count = req->r_dir_release_cnt;
-				fi->dir_ordered_count = req->r_dir_ordered_cnt;
+				dfi->dir_release_count = req->r_dir_release_cnt;
+				dfi->dir_ordered_count = req->r_dir_ordered_cnt;
 			}
 		} else {
 			dout("readdir !did_prepopulate\n");
 			/* disable readdir cache */
-			fi->readdir_cache_idx = -1;
+			dfi->readdir_cache_idx = -1;
 			/* preclude from marking dir complete */
-			fi->dir_release_count = 0;
+			dfi->dir_release_count = 0;
 		}
 
 		/* note next offset and last dentry name */
@@ -464,19 +464,19 @@ more:
 					rinfo->dir_entries + (rinfo->dir_nr-1);
 			unsigned next_offset = req->r_reply_info.dir_end ?
 					2 : (fpos_off(rde->offset) + 1);
-			err = note_last_dentry(fi, rde->name, rde->name_len,
+			err = note_last_dentry(dfi, rde->name, rde->name_len,
 					       next_offset);
 			if (err)
 				return err;
 		} else if (req->r_reply_info.dir_end) {
-			fi->next_offset = 2;
+			dfi->next_offset = 2;
 			/* keep last name */
 		}
 	}
 
-	rinfo = &fi->last_readdir->r_reply_info;
+	rinfo = &dfi->last_readdir->r_reply_info;
 	dout("readdir frag %x num %d pos %llx chunk first %llx\n",
-	     fi->frag, rinfo->dir_nr, ctx->pos,
+	     dfi->frag, rinfo->dir_nr, ctx->pos,
 	     rinfo->dir_nr ? rinfo->dir_entries[0].offset : 0LL);
 
 	i = 0;
@@ -520,52 +520,55 @@ more:
 		ctx->pos++;
 	}
 
-	ceph_mdsc_put_request(fi->last_readdir);
-	fi->last_readdir = NULL;
+	ceph_mdsc_put_request(dfi->last_readdir);
+	dfi->last_readdir = NULL;
 
-	if (fi->next_offset > 2) {
-		frag = fi->frag;
+	if (dfi->next_offset > 2) {
+		frag = dfi->frag;
 		goto more;
 	}
 
 	/* more frags? */
-	if (!ceph_frag_is_rightmost(fi->frag)) {
-		frag = ceph_frag_next(fi->frag);
+	if (!ceph_frag_is_rightmost(dfi->frag)) {
+		frag = ceph_frag_next(dfi->frag);
 		if (is_hash_order(ctx->pos)) {
 			loff_t new_pos = ceph_make_fpos(ceph_frag_value(frag),
-							fi->next_offset, true);
+							dfi->next_offset, true);
 			if (new_pos > ctx->pos)
 				ctx->pos = new_pos;
 			/* keep last_name */
 		} else {
-			ctx->pos = ceph_make_fpos(frag, fi->next_offset, false);
-			kfree(fi->last_name);
-			fi->last_name = NULL;
+			ctx->pos = ceph_make_fpos(frag, dfi->next_offset,
+							false);
+			kfree(dfi->last_name);
+			dfi->last_name = NULL;
 		}
 		dout("readdir next frag is %x\n", frag);
 		goto more;
 	}
-	fi->flags |= CEPH_F_ATEND;
+	dfi->file_info.flags |= CEPH_F_ATEND;
 
 	/*
 	 * if dir_release_count still matches the dir, no dentries
 	 * were released during the whole readdir, and we should have
 	 * the complete dir contents in our cache.
 	 */
-	if (atomic64_read(&ci->i_release_count) == fi->dir_release_count) {
+	if (atomic64_read(&ci->i_release_count) ==
+					dfi->dir_release_count) {
 		spin_lock(&ci->i_ceph_lock);
-		if (fi->dir_ordered_count == atomic64_read(&ci->i_ordered_count)) {
+		if (dfi->dir_ordered_count ==
+				atomic64_read(&ci->i_ordered_count)) {
 			dout(" marking %p complete and ordered\n", inode);
 			/* use i_size to track number of entries in
 			 * readdir cache */
-			BUG_ON(fi->readdir_cache_idx < 0);
-			i_size_write(inode, fi->readdir_cache_idx *
+			BUG_ON(dfi->readdir_cache_idx < 0);
+			i_size_write(inode, dfi->readdir_cache_idx *
 				     sizeof(struct dentry*));
 		} else {
 			dout(" marking %p complete\n", inode);
 		}
-		__ceph_dir_set_complete(ci, fi->dir_release_count,
-					fi->dir_ordered_count);
+		__ceph_dir_set_complete(ci, dfi->dir_release_count,
+					dfi->dir_ordered_count);
 		spin_unlock(&ci->i_ceph_lock);
 	}
 
@@ -573,25 +576,25 @@ more:
 	return 0;
 }
 
-static void reset_readdir(struct ceph_file_info *fi)
+static void reset_readdir(struct ceph_dir_file_info *dfi)
 {
-	if (fi->last_readdir) {
-		ceph_mdsc_put_request(fi->last_readdir);
-		fi->last_readdir = NULL;
+	if (dfi->last_readdir) {
+		ceph_mdsc_put_request(dfi->last_readdir);
+		dfi->last_readdir = NULL;
 	}
-	kfree(fi->last_name);
-	fi->last_name = NULL;
-	fi->dir_release_count = 0;
-	fi->readdir_cache_idx = -1;
-	fi->next_offset = 2;  /* compensate for . and .. */
-	fi->flags &= ~CEPH_F_ATEND;
+	kfree(dfi->last_name);
+	dfi->last_name = NULL;
+	dfi->dir_release_count = 0;
+	dfi->readdir_cache_idx = -1;
+	dfi->next_offset = 2;  /* compensate for . and .. */
+	dfi->file_info.flags &= ~CEPH_F_ATEND;
 }
 
 /*
  * discard buffered readdir content on seekdir(0), or seek to new frag,
  * or seek prior to current chunk
  */
-static bool need_reset_readdir(struct ceph_file_info *fi, loff_t new_pos)
+static bool need_reset_readdir(struct ceph_dir_file_info *dfi, loff_t new_pos)
 {
 	struct ceph_mds_reply_info_parsed *rinfo;
 	loff_t chunk_offset;
@@ -600,10 +603,10 @@ static bool need_reset_readdir(struct ceph_file_info *fi, loff_t new_pos)
 	if (is_hash_order(new_pos)) {
 		/* no need to reset last_name for a forward seek when
 		 * dentries are sotred in hash order */
-	} else if (fi->frag != fpos_frag(new_pos)) {
+	} else if (dfi->frag != fpos_frag(new_pos)) {
 		return true;
 	}
-	rinfo = fi->last_readdir ? &fi->last_readdir->r_reply_info : NULL;
+	rinfo = dfi->last_readdir ? &dfi->last_readdir->r_reply_info : NULL;
 	if (!rinfo || !rinfo->dir_nr)
 		return true;
 	chunk_offset = rinfo->dir_entries[0].offset;
@@ -613,7 +616,7 @@ static bool need_reset_readdir(struct ceph_file_info *fi, loff_t new_pos)
 
 static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence)
 {
-	struct ceph_file_info *fi = file->private_data;
+	struct ceph_dir_file_info *dfi = file->private_data;
 	struct inode *inode = file->f_mapping->host;
 	loff_t retval;
 
@@ -631,20 +634,20 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence)
 	}
 
 	if (offset >= 0) {
-		if (need_reset_readdir(fi, offset)) {
+		if (need_reset_readdir(dfi, offset)) {
 			dout("dir_llseek dropping %p content\n", file);
-			reset_readdir(fi);
+			reset_readdir(dfi);
 		} else if (is_hash_order(offset) && offset > file->f_pos) {
 			/* for hash offset, we don't know if a forward seek
 			 * is within same frag */
-			fi->dir_release_count = 0;
-			fi->readdir_cache_idx = -1;
+			dfi->dir_release_count = 0;
+			dfi->readdir_cache_idx = -1;
 		}
 
 		if (offset != file->f_pos) {
 			file->f_pos = offset;
 			file->f_version = 0;
-			fi->flags &= ~CEPH_F_ATEND;
+			dfi->file_info.flags &= ~CEPH_F_ATEND;
 		}
 		retval = offset;
 	}
@@ -1352,7 +1355,7 @@ static void ceph_d_prune(struct dentry *dentry)
 static ssize_t ceph_read_dir(struct file *file, char __user *buf, size_t size,
 			     loff_t *ppos)
 {
-	struct ceph_file_info *fi = file->private_data;
+	struct ceph_dir_file_info *dfi = file->private_data;
 	struct inode *inode = file_inode(file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int left;
@@ -1361,12 +1364,12 @@ static ssize_t ceph_read_dir(struct file *file, char __user *buf, size_t size,
 	if (!ceph_test_mount_opt(ceph_sb_to_client(inode->i_sb), DIRSTAT))
 		return -EISDIR;
 
-	if (!fi->dir_info) {
-		fi->dir_info = kmalloc(bufsize, GFP_KERNEL);
-		if (!fi->dir_info)
+	if (!dfi->dir_info) {
+		dfi->dir_info = kmalloc(bufsize, GFP_KERNEL);
+		if (!dfi->dir_info)
 			return -ENOMEM;
-		fi->dir_info_len =
-			snprintf(fi->dir_info, bufsize,
+		dfi->dir_info_len =
+			snprintf(dfi->dir_info, bufsize,
 				"entries:   %20lld\n"
 				" files:    %20lld\n"
 				" subdirs:  %20lld\n"
@@ -1386,10 +1389,10 @@ static ssize_t ceph_read_dir(struct file *file, char __user *buf, size_t size,
 				(long)ci->i_rctime.tv_nsec);
 	}
 
-	if (*ppos >= fi->dir_info_len)
+	if (*ppos >= dfi->dir_info_len)
 		return 0;
-	size = min_t(unsigned, size, fi->dir_info_len-*ppos);
-	left = copy_to_user(buf, fi->dir_info + *ppos, size);
+	size = min_t(unsigned, size, dfi->dir_info_len-*ppos);
+	left = copy_to_user(buf, dfi->dir_info + *ppos, size);
 	if (left == size)
 		return -EFAULT;
 	*ppos += (size - left);