erofs: use meta buffers for inode lookup

This converts the remaining inode lookup part by using metabuf in a
straight-forward way. Except that it doesn't use kmap_atomic()
anymore since we now have to maintain two metabufs together.

After this patch, all uncompressed paths are handled with metabuf
instead of page structure.

Link: https://lore.kernel.org/r/20220316012246.95131-2-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/namei.c b/fs/erofs/namei.c
index 8629e61..554efa3 100644 (file)
--- a/fs/erofs/namei.c
+++ b/fs/erofs/namei.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2017-2018 HUAWEI, Inc.
  *             https://www.huawei.com/
+ * Copyright (C) 2022, Alibaba Cloud
  */
 #include "xattr.h"
 
@@ -86,14 +87,14 @@ static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
        return ERR_PTR(-ENOENT);
 }
 
-static struct page *find_target_block_classic(struct inode *dir,
-                                             struct erofs_qstr *name,
-                                             int *_ndirents)
+static void *find_target_block_classic(struct erofs_buf *target,
+                                      struct inode *dir,
+                                      struct erofs_qstr *name,
+                                      int *_ndirents)
 {
        unsigned int startprfx, endprfx;
        int head, back;
-       struct address_space *const mapping = dir->i_mapping;
-       struct page *candidate = ERR_PTR(-ENOENT);
+       void *candidate = ERR_PTR(-ENOENT);
 
        startprfx = endprfx = 0;
        head = 0;
@@ -101,10 +102,11 @@ static struct page *find_target_block_classic(struct inode *dir,
 
        while (head <= back) {
                const int mid = head + (back - head) / 2;
-               struct page *page = read_mapping_page(mapping, mid, NULL);
+               struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+               struct erofs_dirent *de;
 
-               if (!IS_ERR(page)) {
-                       struct erofs_dirent *de = kmap_atomic(page);
+               de = erofs_bread(&buf, dir, mid, EROFS_KMAP);
+               if (!IS_ERR(de)) {
                        const int nameoff = nameoff_from_disk(de->nameoff,
                                                              EROFS_BLKSIZ);
                        const int ndirents = nameoff / sizeof(*de);
@@ -113,13 +115,12 @@ static struct page *find_target_block_classic(struct inode *dir,
                        struct erofs_qstr dname;
 
                        if (!ndirents) {
-                               kunmap_atomic(de);
-                               put_page(page);
+                               erofs_put_metabuf(&buf);
                                erofs_err(dir->i_sb,
                                          "corrupted dir block %d @ nid %llu",
                                          mid, EROFS_I(dir)->nid);
                                DBG_BUGON(1);
-                               page = ERR_PTR(-EFSCORRUPTED);
+                               de = ERR_PTR(-EFSCORRUPTED);
                                goto out;
                        }
 
@@ -135,7 +136,6 @@ static struct page *find_target_block_classic(struct inode *dir,
 
                        /* string comparison without already matched prefix */
                        diff = erofs_dirnamecmp(name, &dname, &matched);
-                       kunmap_atomic(de);
 
                        if (!diff) {
                                *_ndirents = 0;
@@ -145,11 +145,12 @@ static struct page *find_target_block_classic(struct inode *dir,
                                startprfx = matched;
 
                                if (!IS_ERR(candidate))
-                                       put_page(candidate);
-                               candidate = page;
+                                       erofs_put_metabuf(target);
+                               *target = buf;
+                               candidate = de;
                                *_ndirents = ndirents;
                        } else {
-                               put_page(page);
+                               erofs_put_metabuf(&buf);
 
                                back = mid - 1;
                                endprfx = matched;
@@ -158,8 +159,8 @@ static struct page *find_target_block_classic(struct inode *dir,
                }
 out:           /* free if the candidate is valid */
                if (!IS_ERR(candidate))
-                       put_page(candidate);
-               return page;
+                       erofs_put_metabuf(target);
+               return de;
        }
        return candidate;
 }
@@ -169,8 +170,7 @@ int erofs_namei(struct inode *dir,
                erofs_nid_t *nid, unsigned int *d_type)
 {
        int ndirents;
-       struct page *page;
-       void *data;
+       struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
        struct erofs_dirent *de;
        struct erofs_qstr qn;
 
@@ -181,26 +181,20 @@ int erofs_namei(struct inode *dir,
        qn.end = name->name + name->len;
 
        ndirents = 0;
-       page = find_target_block_classic(dir, &qn, &ndirents);
 
-       if (IS_ERR(page))
-               return PTR_ERR(page);
+       de = find_target_block_classic(&buf, dir, &qn, &ndirents);
+       if (IS_ERR(de))
+               return PTR_ERR(de);
 
-       data = kmap_atomic(page);
        /* the target page has been mapped */
        if (ndirents)
-               de = find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents);
-       else
-               de = (struct erofs_dirent *)data;
+               de = find_target_dirent(&qn, (u8 *)de, EROFS_BLKSIZ, ndirents);
 
        if (!IS_ERR(de)) {
                *nid = le64_to_cpu(de->nid);
                *d_type = de->file_type;
        }
-
-       kunmap_atomic(data);
-       put_page(page);
-
+       erofs_put_metabuf(&buf);
        return PTR_ERR_OR_ZERO(de);
 }