[PATCH RFC v2 2/2] erofs: apply the page cache share feature

[Hongzhen Luo <hongzhen@linux.alibaba.com>]

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

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
---
v2: Make adjustments based on the latest implementation.
v1: https://lore.kernel.org/all/20240722065355.1396365-5-hongzhen@linux.alibaba.com/
---
 fs/erofs/inode.c | 23 +++++++++++++++++++++++
 fs/erofs/super.c | 23 +++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 5f6439a63af7..9f1e7332cff9 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 +338,16 @@ 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) {
+				iget_failed(inode);
+				return ERR_PTR(err);
+			}
+		}
+#endif
 	}
 	return inode;
 }
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 35268263aaed..a42e65ef7fc7 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -11,6 +11,7 @@
 #include <linux/fs_parser.h>
 #include <linux/exportfs.h>
 #include "xattr.h"
+#include "pagecache_share.h"
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/erofs.h>
@@ -95,6 +96,10 @@ 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);
+	init_rwsem(&vi->pcs_rwsem);
+#endif
 	return &vi->vfs_inode;
 }
 
@@ -108,6 +113,21 @@ 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.");
+		kfree(vi->fprt);
+		vi->fprt = NULL;
+	}
+}
+#endif
+
 static bool check_layout_compatibility(struct super_block *sb,
 				       struct erofs_super_block *dsb)
 {
@@ -937,6 +957,9 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 const struct super_operations erofs_sops = {
 	.put_super = erofs_put_super,
 	.alloc_inode = erofs_alloc_inode,
+#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
+	.destroy_inode = erofs_destroy_inode,
+#endif
 	.free_inode = erofs_free_inode,
 	.statfs = erofs_statfs,
 	.show_options = erofs_show_options,
-- 
2.43.5