Re: [PATCH] erofs: simplify readdir operation

From: Gao Xiang
Date: Thu Aug 01 2024 - 05:41:50 EST




On 2024/8/1 11:02, Hongzhen Luo wrote:
 - Use i_size instead of i_size_read() due to immutable fses;

 - Get rid of an unneeded goto since erofs_fill_dentries() also works;

 - Remove unnecessary lines.

Signed-off-by: Hongzhen Luo<hongzhen@xxxxxxxxxxxxxxxxx>
---


BTW, can you send any "kernel" patch to LKML <linux-kernel@xxxxxxxxxxxxxxx>
too? Also you'd better to use "scripts/get_maintainers.pl".


 fs/erofs/dir.c      | 35 ++++++++++++-----------------------
 fs/erofs/internal.h |  2 +-
 2 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index 2193a6710c8f..c3b90abdee37 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -8,19 +8,15 @@

 static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
                    void *dentry_blk, struct erofs_dirent *de,
-                   unsigned int nameoff, unsigned int maxsize)
+                   unsigned int nameoff0, unsigned int maxsize)
 {
-    const struct erofs_dirent *end = dentry_blk + nameoff;
+    const struct erofs_dirent *end = dentry_blk + nameoff0;

     while (de < end) {
-        const char *de_name;
+        unsigned char d_type = fs_ftype_to_dtype(de->file_type);
+        unsigned int nameoff = le16_to_cpu(de->nameoff);
+        const char *de_name = (char *)dentry_blk + nameoff;
         unsigned int de_namelen;
-        unsigned char d_type;
-
-        d_type = fs_ftype_to_dtype(de->file_type);
-
-        nameoff = le16_to_cpu(de->nameoff);
-        de_name = (char *)dentry_blk + nameoff;

         /* the last dirent in the block? */
         if (de + 1 >= end)
@@ -52,21 +48,20 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
     struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
     struct super_block *sb = dir->i_sb;
     unsigned long bsz = sb->s_blocksize;
-    const size_t dirsize = i_size_read(dir);
-    unsigned int i = erofs_blknr(sb, ctx->pos);
     unsigned int ofs = erofs_blkoff(sb, ctx->pos);
     int err = 0;
     bool initial = true;

     buf.mapping = dir->i_mapping;
-    while (ctx->pos < dirsize) {
+    while (ctx->pos < dir->i_size) {
+        erofs_off_t dbstart = ctx->pos - ofs;
         struct erofs_dirent *de;
         unsigned int nameoff, maxsize;

-        de = erofs_bread(&buf, erofs_pos(sb, i), EROFS_KMAP);
+        de = erofs_bread(&buf, dbstart, EROFS_KMAP);
         if (IS_ERR(de)) {
             erofs_err(sb, "fail to readdir of logical block %u of nid %llu",
-                  i, EROFS_I(dir)->nid);
+                  erofs_blknr(sb, dbstart), EROFS_I(dir)->nid);
             err = PTR_ERR(de);
             break;
         }
@@ -79,25 +74,19 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
             break;
         }

-        maxsize = min_t(unsigned int, dirsize - ctx->pos + ofs, bsz);
-
+        maxsize = min_t(unsigned int, dir->i_size - dbstart, bsz);
         /* search dirents at the arbitrary position */
         if (initial) {
             initial = false;
-
             ofs = roundup(ofs, sizeof(struct erofs_dirent));
-            ctx->pos = erofs_pos(sb, i) + ofs;
-            if (ofs >= nameoff)
-                goto skip_this;
+            ctx->pos = dbstart + ofs;
         }

         err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
                       nameoff, maxsize);
         if (err)
             break;
-skip_this:
-        ctx->pos = erofs_pos(sb, i) + maxsize;
-        ++i;
+        ctx->pos = dbstart + maxsize;
         ofs = 0;
     }
     erofs_put_metabuf(&buf);
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 736607675396..45dc15ebd870 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -220,7 +220,7 @@ struct erofs_buf {
 };
 #define __EROFS_BUF_INITIALIZER    ((struct erofs_buf){ .page = NULL })

-#define erofs_blknr(sb, addr)    ((addr) >> (sb)->s_blocksize_bits)
+#define erofs_blknr(sb, addr)    ((erofs_blk_t)((addr) >> (sb)->s_blocksize_bits))
 #define erofs_blkoff(sb, addr)    ((addr) & ((sb)->s_blocksize - 1))
 #define erofs_pos(sb, blk)    ((erofs_off_t)(blk) << (sb)->s_blocksize_bits)
 #define erofs_iblks(i)    (round_up((i)->i_size, i_blocksize(i)) >> (i)->i_blkbits)
-- 2.43.5