ext4: fix dx_map_entry to support 256k directory blocks
The dx_map_entry structure doesn't support over 64KB block size by current usage of its member("offs"). Because "offs" treats an offset of copies of the ext4_dir_entry_2 structure as is. This member size is 16 bits. But real offset for over 64KB(256KB) block size needs 18 bits. However, real offset keeps 4 byte boundary, so lower 2 bits is not used. Therefore, we do the following to fix this limitation: For "store": we divide the real offset by 4 and then store this result to "offs" member. For "use": we multiply "offs" member by 4 and then use this result as real offset. Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -749,7 +749,7 @@ static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,
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ext4fs_dirhash(de->name, de->name_len, &h);
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map_tail--;
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map_tail->hash = h.hash;
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map_tail->offs = (u16) ((char *) de - base);
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map_tail->offs = ((char *) de - base)>>2;
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map_tail->size = le16_to_cpu(de->rec_len);
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count++;
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cond_resched();
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@ -1147,7 +1147,8 @@ dx_move_dirents(char *from, char *to, struct dx_map_entry *map, int count,
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unsigned rec_len = 0;
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while (count--) {
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struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *) (from + map->offs);
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struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *)
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(from + (map->offs<<2));
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rec_len = EXT4_DIR_REC_LEN(de->name_len);
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memcpy (to, de, rec_len);
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((struct ext4_dir_entry_2 *) to)->rec_len =
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