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ext4: allow directory holes

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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
This commit is contained in:
Theodore Ts'o 2019-06-20 21:19:02 -04:00
parent 9382cde8cd
commit 4e19d6b65f
2 changed files with 46 additions and 18 deletions
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19
fs/ext4/dir.c
View File

@ -112,7 +112,6 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
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 (IS_ENCRYPTED(inode)) {
@ -148,8 +147,6 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
return err;
}
offset = ctx->pos & (sb->s_blocksize - 1);
while (ctx->pos < inode->i_size) {
struct ext4_map_blocks map;
@ -158,9 +155,18 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
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);
@ -179,13 +185,6 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
}
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;

45
fs/ext4/namei.c
View File

@ -82,8 +82,18 @@ static struct buffer_head *ext4_append(handle_t *handle,
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) \
@ -109,11 +119,14 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
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)) {
@ -980,7 +993,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
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);
@ -1619,7 +1632,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
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;
@ -2203,6 +2216,11 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
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;
@ -2223,6 +2241,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
brelse(bh);
}
bh = ext4_append(handle, dir, &block);
add_to_new_block:
if (IS_ERR(bh)) {
retval = PTR_ERR(bh);
bh = NULL;
@ -2267,7 +2286,7 @@ again:
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;
@ -2815,7 +2834,10 @@ bool ext4_empty_dir(struct inode *inode)
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;
@ -2837,6 +2859,10 @@ bool ext4_empty_dir(struct inode *inode)
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;
@ -3402,7 +3428,10 @@ static struct buffer_head *ext4_get_first_dir_block(handle_t *handle,
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;