erofs: use meta buffers for reading directories

Previously, directory inodes are directly handled with page cache
interfaces.

In order to support sub-page directory blocks and folios, let's
convert them into the latest metabuf infrastructure as well and
this patch addresses the readdir case first.

Link: https://lore.kernel.org/r/20220316012246.95131-1-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 226a57c..780db1e 100644 (file)
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -28,10 +28,10 @@ void erofs_put_metabuf(struct erofs_buf *buf)
        buf->page = NULL;
 }
 
-void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
-                       erofs_blk_t blkaddr, enum erofs_kmap_type type)
+void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
+                 erofs_blk_t blkaddr, enum erofs_kmap_type type)
 {
-       struct address_space *const mapping = sb->s_bdev->bd_inode->i_mapping;
+       struct address_space *const mapping = inode->i_mapping;
        erofs_off_t offset = blknr_to_addr(blkaddr);
        pgoff_t index = offset >> PAGE_SHIFT;
        struct page *page = buf->page;
@@ -60,6 +60,12 @@ void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
        return buf->base + (offset & ~PAGE_MASK);
 }
 
+void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
+                        erofs_blk_t blkaddr, enum erofs_kmap_type type)
+{
+       return erofs_bread(buf, sb->s_bdev->bd_inode, blkaddr, type);
+}
+
 static int erofs_map_blocks_flatmode(struct inode *inode,
                                     struct erofs_map_blocks *map,
                                     int flags)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index eee9b0b..18e5982 100644 (file)
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             https://www.huawei.com/
+ * Copyright (C) 2022, Alibaba Cloud
  */
 #include "internal.h"
 
@@ -67,7 +68,7 @@ static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
 static int erofs_readdir(struct file *f, struct dir_context *ctx)
 {
        struct inode *dir = file_inode(f);
-       struct address_space *mapping = dir->i_mapping;
+       struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
        const size_t dirsize = i_size_read(dir);
        unsigned int i = ctx->pos / EROFS_BLKSIZ;
        unsigned int ofs = ctx->pos % EROFS_BLKSIZ;
@@ -75,26 +76,19 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
        bool initial = true;
 
        while (ctx->pos < dirsize) {
-               struct page *dentry_page;
                struct erofs_dirent *de;
                unsigned int nameoff, maxsize;
 
-               dentry_page = read_mapping_page(mapping, i, NULL);
-               if (dentry_page == ERR_PTR(-ENOMEM)) {
-                       err = -ENOMEM;
-                       break;
-               } else if (IS_ERR(dentry_page)) {
+               de = erofs_bread(&buf, dir, i, EROFS_KMAP);
+               if (IS_ERR(de)) {
                        erofs_err(dir->i_sb,
                                  "fail to readdir of logical block %u of nid %llu",
                                  i, EROFS_I(dir)->nid);
-                       err = -EFSCORRUPTED;
+                       err = PTR_ERR(de);
                        break;
                }
 
-               de = (struct erofs_dirent *)kmap(dentry_page);
-
                nameoff = le16_to_cpu(de->nameoff);
-
                if (nameoff < sizeof(struct erofs_dirent) ||
                    nameoff >= PAGE_SIZE) {
                        erofs_err(dir->i_sb,
@@ -119,10 +113,6 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
                err = erofs_fill_dentries(dir, ctx, de, &ofs,
                                          nameoff, maxsize);
 skip_this:
-               kunmap(dentry_page);
-
-               put_page(dentry_page);
-
                ctx->pos = blknr_to_addr(i) + ofs;
 
                if (err)
@@ -130,6 +120,7 @@ skip_this:
                ++i;
                ofs = 0;
        }
+       erofs_put_metabuf(&buf);
        return err < 0 ? err : 0;
 }
 

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 5aa2cf2..5298c4e 100644 (file)
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -479,6 +479,8 @@ struct erofs_map_dev {
 extern const struct file_operations erofs_file_fops;
 void erofs_unmap_metabuf(struct erofs_buf *buf);
 void erofs_put_metabuf(struct erofs_buf *buf);
+void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
+                 erofs_blk_t blkaddr, enum erofs_kmap_type type);
 void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
                         erofs_blk_t blkaddr, enum erofs_kmap_type type);
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *dev);