[PATCH RFC 4/4] erofs: apply the page cache share feature

[Hongzhen Luo]

This modifies relevant functions to apply the page cache
share feature.

Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
---
 fs/erofs/inode.c | 21 +++++++++++++++++++++
 fs/erofs/super.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 5f6439a63af7..a5c47f69c2db 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2021, Alibaba Cloud
  */
 #include "xattr.h"
+#include "pagecache_share.h"
 
 #include <trace/events/erofs.h>
 
@@ -229,10 +230,22 @@ static int erofs_fill_inode(struct inode *inode)
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_op = &erofs_generic_iops;
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+		erofs_pcs_fill_inode(inode);
+#endif
 		if (erofs_inode_is_data_compressed(vi->datalayout))
 			inode->i_fop = &generic_ro_fops;
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+		else {
+			if (vi->fprt_len > 0)
+				inode->i_fop = &erofs_pcs_file_fops;
+			else
+				inode->i_fop = &erofs_file_fops;
+		}
+#else
 		else
 			inode->i_fop = &erofs_file_fops;
+#endif
 		break;
 	case S_IFDIR:
 		inode->i_op = &erofs_dir_iops;
@@ -325,6 +338,14 @@ struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid)
 			return ERR_PTR(err);
 		}
 		unlock_new_inode(inode);
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+		if ((inode->i_mode & S_IFMT) == S_IFREG &&
+		    EROFS_I(inode)->fprt_len > 0) {
+			err = erofs_pcs_add(inode);
+			if (err)
+				return ERR_PTR(err);
+		}
+#endif
 	}
 	return inode;
 }
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 5ae597c18e75..0377a032d1d7 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -12,6 +12,7 @@
 #include <linux/exportfs.h>
 #include <linux/pseudo_fs.h>
 #include "xattr.h"
+#include "pagecache_share.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/erofs.h>
@@ -96,6 +97,9 @@ static struct inode *erofs_alloc_inode(struct super_block *sb)
 
 	/* zero out everything except vfs_inode */
 	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+	INIT_LIST_HEAD(&vi->pcs_list);
+#endif
 	return &vi->vfs_inode;
 }
 
@@ -109,6 +113,23 @@ static void erofs_free_inode(struct inode *inode)
 	kmem_cache_free(erofs_inode_cachep, vi);
 }
 
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+static void erofs_destroy_inode(struct inode *inode)
+{
+	struct erofs_inode *vi = EROFS_I(inode);
+
+	if ((inode->i_mode & S_IFMT) == S_IFREG &&
+	    EROFS_I(inode)->fprt_len > 0) {
+		if (erofs_pcs_remove(inode))
+			erofs_err(inode->i_sb, "pcs: fail to remove inode.");
+		if (vi->fprt) {
+			kfree(vi->fprt);
+			vi->fprt = NULL;
+		}
+	}
+}
+#endif
+
 static bool check_layout_compatibility(struct super_block *sb,
 				       struct erofs_super_block *dsb)
 {
@@ -685,6 +706,11 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (err)
 		return err;
 
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+	err = erofs_pcs_init_mnt();
+	if (err)
+		return err;
+#endif
 	erofs_info(sb, "mounted with root inode @ nid %llu.", sbi->root_nid);
 	return 0;
 }
@@ -795,6 +821,9 @@ static void erofs_kill_sb(struct super_block *sb)
 	else
 		kill_block_super(sb);
 
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+	(void)erofs_pcs_free_mnt();
+#endif
 	erofs_free_dev_context(sbi->devs);
 	fs_put_dax(sbi->dax_dev, NULL);
 	erofs_fscache_unregister_fs(sb);
@@ -951,6 +980,9 @@ const struct super_operations erofs_sops = {
 	.put_super = erofs_put_super,
 	.alloc_inode = erofs_alloc_inode,
 	.free_inode = erofs_free_inode,
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+	.destroy_inode = erofs_destroy_inode,
+#endif
 	.statfs = erofs_statfs,
 	.show_options = erofs_show_options,
 };
-- 
2.43.5