From c4d8b0235aa98f8c26bf94d308be3fdd24154572 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Fri, 19 Apr 2013 17:55:33 -0400 Subject: [PATCH] ext4: fix readdir error in case inline_data+^dir_index. Zach reported a problem that if inline data is enabled, we don't tell the difference between the offset of '.' and '..'. And a getdents will fail if the user only want to get '.'. And what's worse, we may meet with duplicate dir entries as the offset for inline dir and non-inline one is quite different. This patch just try to resolve this problem if dir_index is disabled. In this case, f_pos is the real offset with the dir block, so for inline dir, we just pretend as if we are a dir block and returns the offset like a norml dir block does. Reported-by: Zach Brown Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" --- fs/ext4/inline.c | 69 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 51 insertions(+), 18 deletions(-) diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index abf8b6278c3a..3e2bf873e8a8 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -1396,6 +1396,14 @@ out: return ret; } +/* + * So this function is called when the volume is mkfsed with + * dir_index disabled. In order to keep f_pos persistent + * after we convert from an inlined dir to a blocked based, + * we just pretend that we are a normal dir and return the + * offset as if '.' and '..' really take place. + * + */ int ext4_read_inline_dir(struct file *filp, void *dirent, filldir_t filldir, int *has_inline_data) @@ -1409,6 +1417,7 @@ int ext4_read_inline_dir(struct file *filp, int ret, inline_size = 0; struct ext4_iloc iloc; void *dir_buf = NULL; + int dotdot_offset, dotdot_size, extra_offset, extra_size; ret = ext4_get_inode_loc(inode, &iloc); if (ret) @@ -1437,8 +1446,21 @@ int ext4_read_inline_dir(struct file *filp, sb = inode->i_sb; stored = 0; parent_ino = le32_to_cpu(((struct ext4_dir_entry_2 *)dir_buf)->inode); + offset = filp->f_pos; + + /* + * dotdot_offset and dotdot_size is the real offset and + * size for ".." and "." if the dir is block based while + * the real size for them are only EXT4_INLINE_DOTDOT_SIZE. + * So we will use extra_offset and extra_size to indicate them + * during the inline dir iteration. + */ + dotdot_offset = EXT4_DIR_REC_LEN(1); + dotdot_size = dotdot_offset + EXT4_DIR_REC_LEN(2); + extra_offset = dotdot_size - EXT4_INLINE_DOTDOT_SIZE; + extra_size = extra_offset + inline_size; - while (!error && !stored && filp->f_pos < inode->i_size) { + while (!error && !stored && filp->f_pos < extra_size) { revalidate: /* * If the version has changed since the last call to @@ -1447,15 +1469,23 @@ revalidate: * dir to make sure. */ if (filp->f_version != inode->i_version) { - for (i = 0; - i < inode->i_size && i < offset;) { + for (i = 0; i < extra_size && i < offset;) { + /* + * "." is with offset 0 and + * ".." is dotdot_offset. + */ if (!i) { - /* skip "." and ".." if needed. */ - i += EXT4_INLINE_DOTDOT_SIZE; + i = dotdot_offset; + continue; + } else if (i == dotdot_offset) { + i = dotdot_size; continue; } + /* for other entry, the real offset in + * the buf has to be tuned accordingly. + */ de = (struct ext4_dir_entry_2 *) - (dir_buf + i); + (dir_buf + i - extra_offset); /* It's too expensive to do a full * dirent test each time round this * loop, but we do have to test at @@ -1463,43 +1493,47 @@ revalidate: * failure will be detected in the * dirent test below. */ if (ext4_rec_len_from_disk(de->rec_len, - inline_size) < EXT4_DIR_REC_LEN(1)) + extra_size) < EXT4_DIR_REC_LEN(1)) break; i += ext4_rec_len_from_disk(de->rec_len, - inline_size); + extra_size); } offset = i; filp->f_pos = offset; filp->f_version = inode->i_version; } - while (!error && filp->f_pos < inode->i_size) { + while (!error && filp->f_pos < extra_size) { if (filp->f_pos == 0) { error = filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR); if (error) break; stored++; + filp->f_pos = dotdot_offset; + continue; + } - error = filldir(dirent, "..", 2, 0, parent_ino, - DT_DIR); + if (filp->f_pos == dotdot_offset) { + error = filldir(dirent, "..", 2, + dotdot_offset, + parent_ino, DT_DIR); if (error) break; stored++; - filp->f_pos = offset = EXT4_INLINE_DOTDOT_SIZE; + filp->f_pos = dotdot_size; continue; } - de = (struct ext4_dir_entry_2 *)(dir_buf + offset); + de = (struct ext4_dir_entry_2 *) + (dir_buf + filp->f_pos - extra_offset); if (ext4_check_dir_entry(inode, filp, de, iloc.bh, dir_buf, - inline_size, offset)) { + extra_size, filp->f_pos)) { ret = stored; goto out; } - offset += ext4_rec_len_from_disk(de->rec_len, - inline_size); if (le32_to_cpu(de->inode)) { /* We might block in the next section * if the data destination is @@ -1522,9 +1556,8 @@ revalidate: stored++; } filp->f_pos += ext4_rec_len_from_disk(de->rec_len, - inline_size); + extra_size); } - offset = 0; } out: kfree(dir_buf); -- 2.30.2