driver/dir.c: introduce *yaf_iterate_shared*

driver/dir.c

@@ -1,8 +1,82 @@
-#include "../include/dir.h"
+#include <asm-generic/errno-base.h>
+#include <linux/buffer_head.h>
+#include <linux/fs_types.h>
+#include <linux/stat.h>
+#include "../include/inode.h"
+#include "../include/yaf.h"
+
+/*
+ * called when the VFS needs to read the directory contents.
+ *
+ * Iterate over the files contained in dir and commit them to @ctx
+ */
+static int yaf_iterate_shared(struct file *dir, struct dir_context *ctx) {
+    struct inode *dinode = file_inode(dir);
+    struct super_block *sb = dinode->i_sb;
+    Yaf_Inode_Info *dyii = YAF_INODE(dinode);
+    uint64_t doff;
+
+    /* ensure that dir is a directory */
+    if (!S_ISDIR(dinode->i_mode)) {
+        log(LOG_ERR, "@dir is not a directory");
+        return -ENOTDIR;
+    }
+
+    /* commit possible *.* and *..* to @ctx */
+    if (!dir_emit_dots(dir, ctx)) {
+        log(LOG_ERR, "dir_emit_dots() failed");
+        return 0;
+    }
+
+    if (ctx->pos == 2) {
+        doff = 0;
+    } else {
+        // ctx->pos > 2
+        doff = ctx->pos - 2;
+
+        /* validate the @ctx->pos */
+        if (doff % YAF_DENTRY_SIZE) {
+            log(LOG_ERR, "@ctx->pos = %lld is not valid", ctx->pos);
+            return -ENOENT;
+        }
+    }
+
+    /* iterate files in the directory from doff */
+    while(doff < dinode->i_size) {
+        Yaf_Dentry *yd;
+        uint64_t iboff = doff % DENTRYS_PER_BLOCK;
+        struct buffer_head *bh = sb_bread(sb,
+                    INO2BID(sb, dyii->i_block[doff / DENTRYS_PER_BLOCK]));
+        if (!bh) {
+            log(LOG_ERR, "sb_bread() failed");
+            return -EIO;
+        }
+
+        yd = (Yaf_Dentry *)(bh->b_data);
+        for(int i = iboff / YAF_DENTRY_SIZE; i < DENTRYS_PER_BLOCK;
+            ++i, doff += YAF_DENTRY_SIZE) {
+            if (yd->d_ino != RESERVED_INO) {
+                if (!dir_emit(ctx, yd->d_name, yd->d_name_len,
+                              yd->d_ino, DT_UNKNOWN)) {
+                    log(LOG_ERR, "dir_emit() for %s failed", yd->d_name);
+                }
+            }
+        }
+
+        brelse(bh);
+    }
+
+    /* update the @ctx->pos */
+    ctx->pos = doff + 2;
+
+    return 0;
+}
 
 /*
  * describes how the VFS can manipulate an open file accroding to
  * https://docs.kernel.org/next/filesystems/vfs.html#struct-file-operations
  */
 const struct file_operations yaf_dir_ops = {
+    .iterate_shared = yaf_iterate_shared, /* called when the VFS needs to
+                                read the directory contents */
 };

include/dir.h

@@ -3,7 +3,7 @@
     #define __DIR_H_
 
     #ifdef __KERNEL__
-        #include "linux/fs.h"
+        #include <linux/fs.h>
     #endif
 
     extern const struct file_operations yaf_dir_ops;

test.py

@@ -93,6 +93,8 @@ def kill(self) -> None:
         logger.info("mount the device")
         qemu.execute("mount -t yaf /dev/vda test")
 
+        qemu.execute("ls -a test")
+
         logger.info("umount the device")
         qemu.execute("umount test")