nilfs2: localize highmem mapping for checkpoint reading within cpfile

Move the code for reading from a checkpoint entry that is performed in
nilfs_attach_checkpoint() to the cpfile side, and make the page mapping
local and temporary.  And use kmap_local instead of kmap to access the
checkpoint entry page.

In order to load the ifile inode information included in the checkpoint
entry within the inode lock section of nilfs_ifile_read(), the newly added
checkpoint reading method nilfs_cpfile_read_checkpoint() is called
indirectly via nilfs_ifile_read() instead of from
nilfs_attach_checkpoint().

Link: https://lkml.kernel.org/r/20240122140202.6950-14-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/fs/nilfs2/ifile.c b/fs/nilfs2/ifile.c
index e9538fa46ff2..612e609158b5 100644
--- a/fs/nilfs2/ifile.c
+++ b/fs/nilfs2/ifile.c
@@ -15,6 +15,7 @@
 #include "mdt.h"
 #include "alloc.h"
 #include "ifile.h"
+#include "cpfile.h"
 
 /**
  * struct nilfs_ifile_info - on-memory private data of ifile
@@ -173,14 +174,18 @@ int nilfs_ifile_count_free_inodes(struct inode *ifile,
  * nilfs_ifile_read - read or get ifile inode
  * @sb: super block instance
  * @root: root object
+ * @cno: number of checkpoint entry to read
  * @inode_size: size of an inode
- * @raw_inode: on-disk ifile inode
- * @inodep: buffer to store the inode
+ *
+ * Return: 0 on success, or the following negative error code on failure.
+ * * %-EINVAL	- Invalid checkpoint.
+ * * %-ENOMEM	- Insufficient memory available.
+ * * %-EIO	- I/O error (including metadata corruption).
  */
 int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
-		     size_t inode_size, struct nilfs_inode *raw_inode,
-		     struct inode **inodep)
+		     __u64 cno, size_t inode_size)
 {
+	struct the_nilfs *nilfs;
 	struct inode *ifile;
 	int err;
 
@@ -201,13 +206,13 @@ int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
 
 	nilfs_palloc_setup_cache(ifile, &NILFS_IFILE_I(ifile)->palloc_cache);
 
-	err = nilfs_read_inode_common(ifile, raw_inode);
+	nilfs = sb->s_fs_info;
+	err = nilfs_cpfile_read_checkpoint(nilfs->ns_cpfile, cno, root, ifile);
 	if (err)
 		goto failed;
 
 	unlock_new_inode(ifile);
  out:
-	*inodep = ifile;
 	return 0;
  failed:
 	iget_failed(ifile);