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ext4: Scan all directory blocks when looking up an entry

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Scanning only the direct blocks of the directory file may falsely report
an existing file as nonexisting, and worse can also lead to creation
of a duplicate entry on file creation.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>
This commit is contained in:
Stefan Brüns 2016-09-06 04:36:46 +02:00 committed by Tom Rini
parent 10a7a1b8ba
commit b7dd40d052
1 changed files with 40 additions and 44 deletions
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84
fs/ext4/ext4_common.c
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@ -525,64 +525,57 @@ static int search_dir(struct ext2_inode *parent_inode, char *dirname)
{
int status;
int inodeno = 0;
int totalbytes;
int templength;
int direct_blk_idx;
int offset;
int blk_idx;
long int blknr;
char *ptr = NULL;
unsigned char *block_buffer = NULL;
char *block_buffer = NULL;
struct ext2_dirent *dir = NULL;
struct ext_filesystem *fs = get_fs();
uint32_t directory_blocks;
char *direntname;
/* read the block no allocated to a file */
for (direct_blk_idx = 0; direct_blk_idx < INDIRECT_BLOCKS;
direct_blk_idx++) {
blknr = read_allocated_block(parent_inode, direct_blk_idx);
directory_blocks = le32_to_cpu(parent_inode->size) >>
LOG2_BLOCK_SIZE(ext4fs_root);
block_buffer = zalloc(fs->blksz);
if (!block_buffer)
goto fail;
/* get the block no allocated to a file */
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(parent_inode, blk_idx);
if (blknr == 0)
goto fail;
/* read the blocks of parent inode */
block_buffer = zalloc(fs->blksz);
if (!block_buffer)
goto fail;
/* read the directory block */
status = ext4fs_devread((lbaint_t)blknr * fs->sect_perblk,
0, fs->blksz, (char *)block_buffer);
if (status == 0)
goto fail;
dir = (struct ext2_dirent *)block_buffer;
ptr = (char *)dir;
totalbytes = 0;
while (le16_to_cpu(dir->direntlen) >= 0) {
/*
* blocksize-totalbytes because last directory
* length i.e.,*dir->direntlen is free availble
* space in the block that means
* it is a last entry of directory entry
*/
if (dir->inode && (strlen(dirname) == dir->namelen)) {
if (strncmp(dirname, ptr + sizeof(struct ext2_dirent), dir->namelen) == 0) {
inodeno = le32_to_cpu(dir->inode);
break;
}
}
offset = 0;
do {
dir = (struct ext2_dirent *)(block_buffer + offset);
direntname = (char*)(dir) + sizeof(struct ext2_dirent);
if (fs->blksz - totalbytes == le16_to_cpu(dir->direntlen))
int direntlen = le16_to_cpu(dir->direntlen);
if (direntlen < sizeof(struct ext2_dirent))
break;
/* traversing the each directory entry */
templength = le16_to_cpu(dir->direntlen);
totalbytes = totalbytes + templength;
dir = (struct ext2_dirent *)((char *)dir + templength);
ptr = (char *)dir;
}
if (dir->inode && (strlen(dirname) == dir->namelen) &&
(strncmp(dirname, direntname, dir->namelen) == 0)) {
inodeno = le32_to_cpu(dir->inode);
break;
}
free(block_buffer);
block_buffer = NULL;
offset += direntlen;
if (inodeno > 0)
} while (offset < fs->blksz);
if (inodeno > 0) {
free(block_buffer);
return inodeno;
}
}
fail:
@ -834,14 +827,17 @@ fail:
int ext4fs_filename_unlink(char *filename)
{
short direct_blk_idx = 0;
int blk_idx;
long int blknr = -1;
int inodeno = -1;
uint32_t directory_blocks;
directory_blocks = le32_to_cpu(g_parent_inode->size) >>
LOG2_BLOCK_SIZE(ext4fs_root);
/* read the block no allocated to a file */
for (direct_blk_idx = 0; direct_blk_idx < INDIRECT_BLOCKS;
direct_blk_idx++) {
blknr = read_allocated_block(g_parent_inode, direct_blk_idx);
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(g_parent_inode, blk_idx);
if (blknr == 0)
break;
inodeno = unlink_filename(filename, blknr);