[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>

1 files changed, 101 insertions, 123 deletions

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 204d8614406f..ba824964b9bb 100644
--- 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)