[PATCH] fat: Remove duplicate directory scanning code

This patch removes duplicate directory scanning code from fs/fat/dir.c.  The
two functions that share identical code are fat_readdirx() and
fat_search_long().  This patch also renames fat_readdirx to __fat_readdir().

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 204d861..ba82496 100644 (file)
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -222,6 +222,80 @@ fat_shortname2uni(struct nls_table *nls, unsigned char *buf, int buf_size,
        return len;
 }
 
+enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, };
+
+/**
+ * fat_parse_long - Parse extended directory entry.
+ *
+ * This function returns zero on success, negative value on error, or one of
+ * the following:
+ *
+ * %PARSE_INVALID - Directory entry is invalid.
+ * %PARSE_NOT_LONGNAME - Directory entry does not contain longname.
+ * %PARSE_EOF - Directory has no more entries.
+ */
+static int fat_parse_long(struct inode *dir, loff_t *pos,
+                         struct buffer_head **bh, struct msdos_dir_entry **de,
+                         wchar_t **unicode, unsigned char *nr_slots)
+{
+       struct msdos_dir_slot *ds;
+       unsigned char id, slot, slots, alias_checksum;
+
+       if (!*unicode) {
+               *unicode = (wchar_t *)__get_free_page(GFP_KERNEL);
+               if (!*unicode) {
+                       brelse(*bh);
+                       return -ENOMEM;
+               }
+       }
+parse_long:
+       slots = 0;
+       ds = (struct msdos_dir_slot *)*de;
+       id = ds->id;
+       if (!(id & 0x40))
+               return PARSE_INVALID;
+       slots = id & ~0x40;
+       if (slots > 20 || !slots)       /* ceil(256 * 2 / 26) */
+               return PARSE_INVALID;
+       *nr_slots = slots;
+       alias_checksum = ds->alias_checksum;
+
+       slot = slots;
+       while (1) {
+               int offset;
+
+               slot--;
+               offset = slot * 13;
+               fat16_towchar(*unicode + offset, ds->name0_4, 5);
+               fat16_towchar(*unicode + offset + 5, ds->name5_10, 6);
+               fat16_towchar(*unicode + offset + 11, ds->name11_12, 2);
+
+               if (ds->id & 0x40)
+                       (*unicode)[offset + 13] = 0;
+               if (fat_get_entry(dir, pos, bh, de) < 0)
+                       return PARSE_EOF;
+               if (slot == 0)
+                       break;
+               ds = (struct msdos_dir_slot *)*de;
+               if (ds->attr != ATTR_EXT)
+                       return PARSE_NOT_LONGNAME;
+               if ((ds->id & ~0x40) != slot)
+                       goto parse_long;
+               if (ds->alias_checksum != alias_checksum)
+                       goto parse_long;
+       }
+       if ((*de)->name[0] == DELETED_FLAG)
+               return PARSE_INVALID;
+       if ((*de)->attr == ATTR_EXT)
+               goto parse_long;
+       if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
+               return PARSE_INVALID;
+       if (fat_checksum((*de)->name) != alias_checksum)
+               *nr_slots = 0;
+
+       return 0;
+}
+
 /*
  * Return values: negative -> error, 0 -> not found, positive -> found,
  * value is the total amount of slots, including the shortname entry.
@@ -259,65 +333,16 @@ parse_record:
                if (de->attr != ATTR_EXT && IS_FREE(de->name))
                        continue;
                if (de->attr == ATTR_EXT) {
-                       struct msdos_dir_slot *ds;
-                       unsigned char id;
-                       unsigned char slot;
-                       unsigned char slots;
-                       unsigned char alias_checksum;
-
-                       if (!unicode) {
-                               unicode = (wchar_t *)
-                                       __get_free_page(GFP_KERNEL);
-                               if (!unicode) {
-                                       brelse(bh);
-                                       return -ENOMEM;
-                               }
-                       }
-parse_long:
-                       slots = 0;
-                       ds = (struct msdos_dir_slot *) de;
-                       id = ds->id;
-                       if (!(id & 0x40))
-                               continue;
-                       slots = id & ~0x40;
-                       if (slots > 20 || !slots)       /* ceil(256 * 2 / 26) */
-                               continue;
-                       nr_slots = slots;
-                       alias_checksum = ds->alias_checksum;
-
-                       slot = slots;
-                       while (1) {
-                               int offset;
-
-                               slot--;
-                               offset = slot * 13;
-                               fat16_towchar(unicode + offset, ds->name0_4, 5);
-                               fat16_towchar(unicode + offset + 5, ds->name5_10, 6);
-                               fat16_towchar(unicode + offset + 11, ds->name11_12, 2);
-
-                               if (ds->id & 0x40) {
-                                       unicode[offset + 13] = 0;
-                               }
-                               if (fat_get_entry(inode, &cpos, &bh, &de) < 0)
-                                       goto EODir;
-                               if (slot == 0)
-                                       break;
-                               ds = (struct msdos_dir_slot *) de;
-                               if (ds->attr !=  ATTR_EXT)
-                                       goto parse_record;
-                               if ((ds->id & ~0x40) != slot)
-                                       goto parse_long;
-                               if (ds->alias_checksum != alias_checksum)
-                                       goto parse_long;
-                       }
-                       if (de->name[0] == DELETED_FLAG)
-                               continue;
-                       if (de->attr ==  ATTR_EXT)
-                               goto parse_long;
-                       if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME))
+                       int status = fat_parse_long(inode, &cpos, &bh, &de,
+                                                   &unicode, &nr_slots);
+                       if (status < 0)
+                               return status;
+                       else if (status == PARSE_INVALID)
                                continue;
-                       if (fat_checksum(de->name) != alias_checksum)
-                               nr_slots = 0;
+                       else if (status == PARSE_NOT_LONGNAME)
+                               goto parse_record;
+                       else if (status == PARSE_EOF)
+                               goto EODir;
                }
 
                memcpy(work, de->name, sizeof(de->name));
@@ -405,8 +430,8 @@ struct fat_ioctl_filldir_callback {
        int short_len;
 };
 
-static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent,
-                       filldir_t filldir, int short_only, int both)
+static int __fat_readdir(struct inode *inode, struct file *filp, void *dirent,
+                        filldir_t filldir, int short_only, int both)
 {
        struct super_block *sb = inode->i_sb;
        struct msdos_sb_info *sbi = MSDOS_SB(sb);
@@ -455,9 +480,10 @@ static int fat_readdirx(struct inode *inode, struct file *filp, void *dirent,
 
        bh = NULL;
 GetNew:
-       long_slots = 0;
        if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
                goto EODir;
+parse_record:
+       long_slots = 0;
        /* Check for long filename entry */
        if (isvfat) {
                if (de->name[0] == DELETED_FLAG)
@@ -472,66 +498,18 @@ GetNew:
        }
 
        if (isvfat && de->attr == ATTR_EXT) {
-               struct msdos_dir_slot *ds;
-               unsigned char id;
-               unsigned char slot;
-               unsigned char slots;
-               unsigned char alias_checksum;
-
-               if (!unicode) {
-                       unicode = (wchar_t *)__get_free_page(GFP_KERNEL);
-                       if (!unicode) {
-                               filp->f_pos = cpos;
-                               brelse(bh);
-                               ret = -ENOMEM;
-                               goto out;
-                       }
-               }
-ParseLong:
-               slots = 0;
-               ds = (struct msdos_dir_slot *) de;
-               id = ds->id;
-               if (!(id & 0x40))
-                       goto RecEnd;
-               slots = id & ~0x40;
-               if (slots > 20 || !slots)       /* ceil(256 * 2 / 26) */
+               int status = fat_parse_long(inode, &cpos, &bh, &de,
+                                           &unicode, &long_slots);
+               if (status < 0) {
+                       filp->f_pos = cpos;
+                       ret = status;
+                       goto out;
+               } else if (status == PARSE_INVALID)
                        goto RecEnd;
-               long_slots = slots;
-               alias_checksum = ds->alias_checksum;
-
-               slot = slots;
-               while (1) {
-                       int offset;
-
-                       slot--;
-                       offset = slot * 13;
-                       fat16_towchar(unicode + offset, ds->name0_4, 5);
-                       fat16_towchar(unicode + offset + 5, ds->name5_10, 6);
-                       fat16_towchar(unicode + offset + 11, ds->name11_12, 2);
-
-                       if (ds->id & 0x40) {
-                               unicode[offset + 13] = 0;
-                       }
-                       if (fat_get_entry(inode, &cpos, &bh, &de) == -1)
-                               goto EODir;
-                       if (slot == 0)
-                               break;
-                       ds = (struct msdos_dir_slot *) de;
-                       if (ds->attr !=  ATTR_EXT)
-                               goto RecEnd;    /* XXX */
-                       if ((ds->id & ~0x40) != slot)
-                               goto ParseLong;
-                       if (ds->alias_checksum != alias_checksum)
-                               goto ParseLong;
-               }
-               if (de->name[0] == DELETED_FLAG)
-                       goto RecEnd;
-               if (de->attr ==  ATTR_EXT)
-                       goto ParseLong;
-               if (IS_FREE(de->name) || (de->attr & ATTR_VOLUME))
-                       goto RecEnd;
-               if (fat_checksum(de->name) != alias_checksum)
-                       long_slots = 0;
+               else if (status == PARSE_NOT_LONGNAME)
+                       goto parse_record;
+               else if (status == PARSE_EOF)
+                       goto EODir;
        }
 
        if (sbi->options.dotsOK) {
@@ -665,7 +643,7 @@ out:
 static int fat_readdir(struct file *filp, void *dirent, filldir_t filldir)
 {
        struct inode *inode = filp->f_dentry->d_inode;
-       return fat_readdirx(inode, filp, dirent, filldir, 0, 0);
+       return __fat_readdir(inode, filp, dirent, filldir, 0, 0);
 }
 
 static int fat_ioctl_filldir(void *__buf, const char *name, int name_len,
@@ -754,8 +732,8 @@ static int fat_dir_ioctl(struct inode * inode, struct file * filp,
        down(&inode->i_sem);
        ret = -ENOENT;
        if (!IS_DEADDIR(inode)) {
-               ret = fat_readdirx(inode, filp, &buf, fat_ioctl_filldir,
-                                  short_only, both);
+               ret = __fat_readdir(inode, filp, &buf, fat_ioctl_filldir,
+                                   short_only, both);
        }
        up(&inode->i_sem);
        if (ret >= 0)