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ext4: Correct block number handling, empty block vs. error code

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read_allocated block may return block number 0, which is just an indicator
a chunk of the file is not backed by a block, i.e. it is sparse.

During file deletions, just continue with the next logical block, for other
operations treat blocknumber <= 0 as an error.

For writes, blocknumber 0 should never happen, as U-Boot always allocates
blocks for the whole file.  Reading already handles this correctly, i.e. the
read buffer is 0-fillled.

Not treating block 0 as sparse block leads to FS corruption, e.g.
	./sandbox/u-boot -c 'host bind 0 ./sandbox/test/fs/3GB.ext4.img ;
		ext4write host 0 0 /2.5GB.file 1 '
The 2.5GB.file from the fs test is actually a sparse file.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
This commit is contained in:
Stefan Brüns 2016-09-06 04:36:55 +02:00 • committed by Tom Rini
parent b779e0290a
commit de9e831675
2 changed files with 13 additions and 4 deletions
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6
fs/ext4/ext4_common.c
View file

@ -534,7 +534,7 @@ static int search_dir(struct ext2_inode *parent_inode, char *dirname)
/* get the block no allocated to a file */ /* get the block no allocated to a file */
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) { for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(parent_inode, blk_idx); blknr = read_allocated_block(parent_inode, blk_idx);
if (blknr == 0) if (blknr <= 0)
goto fail; goto fail;
/* read the directory block */ /* read the directory block */
@ -828,7 +828,7 @@ int ext4fs_filename_unlink(char *filename)
/* read the block no allocated to a file */ /* read the block no allocated to a file */
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) { for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(g_parent_inode, blk_idx); blknr = read_allocated_block(g_parent_inode, blk_idx);
if (blknr == 0) if (blknr <= 0)
break; break;
inodeno = unlink_filename(filename, blknr); inodeno = unlink_filename(filename, blknr);
if (inodeno != -1) if (inodeno != -1)
@ -1590,7 +1590,7 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)
if (status == 0) { if (status == 0) {
printf("** SI ext2fs read block (indir 1)" printf("** SI ext2fs read block (indir 1)"
"failed. **\n"); "failed. **\n");
return 0; return -1;
} }
ext4fs_indir1_blkno = ext4fs_indir1_blkno =
le32_to_cpu(inode->b.blocks. le32_to_cpu(inode->b.blocks.

11
fs/ext4/ext4_write.c
View file

@ -461,6 +461,10 @@ static int ext4fs_delete_file(int inodeno)
/* release data blocks */ /* release data blocks */
for (i = 0; i < no_blocks; i++) { for (i = 0; i < no_blocks; i++) {
blknr = read_allocated_block(&inode, i); blknr = read_allocated_block(&inode, i);
if (blknr == 0)
continue;
if (blknr < 0)
goto fail;
bg_idx = blknr / blk_per_grp; bg_idx = blknr / blk_per_grp;
if (fs->blksz == 1024) { if (fs->blksz == 1024) {
remainder = blknr % blk_per_grp; remainder = blknr % blk_per_grp;
@ -718,6 +722,10 @@ void ext4fs_deinit(void)
fs->curr_blkno = 0; fs->curr_blkno = 0;
} }
/*
* Write data to filesystem blocks. Uses same optimization for
* contigous sectors as ext4fs_read_file
*/
static int ext4fs_write_file(struct ext2_inode *file_inode, static int ext4fs_write_file(struct ext2_inode *file_inode,
int pos, unsigned int len, char *buf) int pos, unsigned int len, char *buf)
{ {
@ -744,7 +752,7 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
int blockend = fs->blksz; int blockend = fs->blksz;
int skipfirst = 0; int skipfirst = 0;
blknr = read_allocated_block(file_inode, i); blknr = read_allocated_block(file_inode, i);
if (blknr < 0) if (blknr <= 0)
return -1; return -1;
blknr = blknr << log2_fs_blocksize; blknr = blknr << log2_fs_blocksize;
@ -910,6 +918,7 @@ int ext4fs_write(const char *fname, unsigned char *buffer,
/* copy the file content into data blocks */ /* copy the file content into data blocks */
if (ext4fs_write_file(file_inode, 0, sizebytes, (char *)buffer) == -1) { if (ext4fs_write_file(file_inode, 0, sizebytes, (char *)buffer) == -1) {
printf("Error in copying content\n"); printf("Error in copying content\n");
/* FIXME: Deallocate data blocks */
goto fail; goto fail;
} }
ibmap_idx = parent_inodeno / le32_to_cpu(ext4fs_root->sblock.inodes_per_group); ibmap_idx = parent_inodeno / le32_to_cpu(ext4fs_root->sblock.inodes_per_group);