ext4: allow directory holes
commit 4e19d6b65fb4fc42e352ce9883649e049da14743 upstream.
The largedir feature was intended to allow ext4 directories to have
unmapped directory blocks (e.g., directory holes). And so the
released e2fsprogs no longer enforces this for largedir file systems;
however, the corresponding change to the kernel-side code was not made.
This commit fixes this oversight.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index e16bc4c..0c83bff 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -106,7 +106,6 @@
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct buffer_head *bh = NULL;
- int dir_has_error = 0;
struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
if (ext4_encrypted_inode(inode)) {
@@ -142,8 +141,6 @@
return err;
}
- offset = ctx->pos & (sb->s_blocksize - 1);
-
while (ctx->pos < inode->i_size) {
struct ext4_map_blocks map;
@@ -152,9 +149,18 @@
goto errout;
}
cond_resched();
+ offset = ctx->pos & (sb->s_blocksize - 1);
map.m_lblk = ctx->pos >> EXT4_BLOCK_SIZE_BITS(sb);
map.m_len = 1;
err = ext4_map_blocks(NULL, inode, &map, 0);
+ if (err == 0) {
+ /* m_len should never be zero but let's avoid
+ * an infinite loop if it somehow is */
+ if (map.m_len == 0)
+ map.m_len = 1;
+ ctx->pos += map.m_len * sb->s_blocksize;
+ continue;
+ }
if (err > 0) {
pgoff_t index = map.m_pblk >>
(PAGE_SHIFT - inode->i_blkbits);
@@ -173,13 +179,6 @@
}
if (!bh) {
- if (!dir_has_error) {
- EXT4_ERROR_FILE(file, 0,
- "directory contains a "
- "hole at offset %llu",
- (unsigned long long) ctx->pos);
- dir_has_error = 1;
- }
/* corrupt size? Maybe no more blocks to read */
if (ctx->pos > inode->i_blocks << 9)
break;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 3c3757e..29dc027 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -79,8 +79,18 @@
static int ext4_dx_csum_verify(struct inode *inode,
struct ext4_dir_entry *dirent);
+/*
+ * Hints to ext4_read_dirblock regarding whether we expect a directory
+ * block being read to be an index block, or a block containing
+ * directory entries (and if the latter, whether it was found via a
+ * logical block in an htree index block). This is used to control
+ * what sort of sanity checkinig ext4_read_dirblock() will do on the
+ * directory block read from the storage device. EITHER will means
+ * the caller doesn't know what kind of directory block will be read,
+ * so no specific verification will be done.
+ */
typedef enum {
- EITHER, INDEX, DIRENT
+ EITHER, INDEX, DIRENT, DIRENT_HTREE
} dirblock_type_t;
#define ext4_read_dirblock(inode, block, type) \
@@ -106,11 +116,14 @@
return bh;
}
- if (!bh) {
+ if (!bh && (type == INDEX || type == DIRENT_HTREE)) {
ext4_error_inode(inode, func, line, block,
- "Directory hole found");
+ "Directory hole found for htree %s block",
+ (type == INDEX) ? "index" : "leaf");
return ERR_PTR(-EFSCORRUPTED);
}
+ if (!bh)
+ return NULL;
dirent = (struct ext4_dir_entry *) bh->b_data;
/* Determine whether or not we have an index block */
if (is_dx(inode)) {
@@ -960,7 +973,7 @@
dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu\n",
(unsigned long)block));
- bh = ext4_read_dirblock(dir, block, DIRENT);
+ bh = ext4_read_dirblock(dir, block, DIRENT_HTREE);
if (IS_ERR(bh))
return PTR_ERR(bh);
@@ -1537,7 +1550,7 @@
return (struct buffer_head *) frame;
do {
block = dx_get_block(frame->at);
- bh = ext4_read_dirblock(dir, block, DIRENT);
+ bh = ext4_read_dirblock(dir, block, DIRENT_HTREE);
if (IS_ERR(bh))
goto errout;
@@ -2142,6 +2155,11 @@
blocks = dir->i_size >> sb->s_blocksize_bits;
for (block = 0; block < blocks; block++) {
bh = ext4_read_dirblock(dir, block, DIRENT);
+ if (bh == NULL) {
+ bh = ext4_bread(handle, dir, block,
+ EXT4_GET_BLOCKS_CREATE);
+ goto add_to_new_block;
+ }
if (IS_ERR(bh)) {
retval = PTR_ERR(bh);
bh = NULL;
@@ -2162,6 +2180,7 @@
brelse(bh);
}
bh = ext4_append(handle, dir, &block);
+add_to_new_block:
if (IS_ERR(bh)) {
retval = PTR_ERR(bh);
bh = NULL;
@@ -2203,7 +2222,7 @@
return PTR_ERR(frame);
entries = frame->entries;
at = frame->at;
- bh = ext4_read_dirblock(dir, dx_get_block(frame->at), DIRENT);
+ bh = ext4_read_dirblock(dir, dx_get_block(frame->at), DIRENT_HTREE);
if (IS_ERR(bh)) {
err = PTR_ERR(bh);
bh = NULL;
@@ -2719,7 +2738,10 @@
EXT4_ERROR_INODE(inode, "invalid size");
return true;
}
- bh = ext4_read_dirblock(inode, 0, EITHER);
+ /* The first directory block must not be a hole,
+ * so treat it as DIRENT_HTREE
+ */
+ bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
if (IS_ERR(bh))
return true;
@@ -2741,6 +2763,10 @@
brelse(bh);
lblock = offset >> EXT4_BLOCK_SIZE_BITS(sb);
bh = ext4_read_dirblock(inode, lblock, EITHER);
+ if (bh == NULL) {
+ offset += sb->s_blocksize;
+ continue;
+ }
if (IS_ERR(bh))
return true;
de = (struct ext4_dir_entry_2 *) bh->b_data;
@@ -3302,7 +3328,10 @@
struct buffer_head *bh;
if (!ext4_has_inline_data(inode)) {
- bh = ext4_read_dirblock(inode, 0, EITHER);
+ /* The first directory block must not be a hole, so
+ * treat it as DIRENT_HTREE
+ */
+ bh = ext4_read_dirblock(inode, 0, DIRENT_HTREE);
if (IS_ERR(bh)) {
*retval = PTR_ERR(bh);
return NULL;