[U-Boot] [PATCH v3 04/13] ext4: Scan all directory blocks for space when inserting a new entry

[Lukasz Majewski]

Hi Stefan,

> Previously, only the last directory block was scanned for available
> space. Instead, scan all blocks back to front, and if no sufficient
> space is found, eventually append a new block.
> Blocks are only appended if the directory does not use extents or the
> new block would require insertion of indirect blocks, as the old code
> does.
> 
> Signed-off-by: Stefan Brüns <stefan.bruens at rwth-aachen.de>
> ---
>  fs/ext4/ext4_common.c | 72
> ++++++++++++++++++++------------------------------- 1 file changed,
> 28 insertions(+), 44 deletions(-)
> 
> v3: Patch added to series
> 
> diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
> index 49d6465..96dc371 100644
> --- a/fs/ext4/ext4_common.c
> +++ b/fs/ext4/ext4_common.c
> @@ -365,14 +365,10 @@ int ext4fs_update_parent_dentry(char *filename,
> int file_type) {
>  	unsigned int *zero_buffer = NULL;
>  	char *root_first_block_buffer = NULL;
> -	int direct_blk_idx;
> -	long int root_blknr;
> +	int blk_idx;
>  	long int first_block_no_of_root = 0;
> -	long int previous_blknr = -1;
>  	int totalbytes = 0;
> -	short int padding_factor = 0;
>  	unsigned int new_entry_byte_reqd;
> -	unsigned int last_entry_dirlen;
>  	int sizeof_void_space = 0;
>  	int templength = 0;
>  	int inodeno = -1;
> @@ -384,6 +380,7 @@ int ext4fs_update_parent_dentry(char *filename,
> int file_type) uint32_t new_blk_no;
>  	uint32_t new_size;
>  	uint32_t new_blockcnt;
> +	uint32_t directory_blocks;
>  
>  	zero_buffer = zalloc(fs->blksz);
>  	if (!zero_buffer) {
> @@ -396,19 +393,16 @@ int ext4fs_update_parent_dentry(char *filename,
> int file_type) printf("No Memory\n");
>  		return -1;
>  	}
> +	new_entry_byte_reqd = ROUND(strlen(filename) +
> +				    sizeof(struct ext2_dirent), 4);
>  restart:
> +	directory_blocks = le32_to_cpu(g_parent_inode->size) >>
> +		LOG2_BLOCK_SIZE(ext4fs_root);
> +	blk_idx = directory_blocks - 1;
>  
> +restart_read:
>  	/* read the block no allocated to a file */
> -	for (direct_blk_idx = 0; direct_blk_idx < INDIRECT_BLOCKS;
> -	     direct_blk_idx++) {
> -		root_blknr = read_allocated_block(g_parent_inode,
> -						  direct_blk_idx);
> -		if (root_blknr == 0) {
> -			first_block_no_of_root = previous_blknr;
> -			break;
> -		}
> -		previous_blknr = root_blknr;
> -	}
> +	first_block_no_of_root =
> read_allocated_block(g_parent_inode, blk_idx); 
>  	status = ext4fs_devread((lbaint_t)first_block_no_of_root
>  				* fs->sect_perblk,
> @@ -420,42 +414,33 @@ restart:
>  		goto fail;
>  	dir = (struct ext2_dirent *)root_first_block_buffer;
>  	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
> -		 */
> +		unsigned short used_len = ROUND(dir->namelen +
> +		    sizeof(struct ext2_dirent), 4);
>  
> -		/* traversing the each directory entry */
> +		/* last entry of block */
>  		if (fs->blksz - totalbytes ==
> le16_to_cpu(dir->direntlen)) {
> -			if (strlen(filename) % 4 != 0)
> -				padding_factor = 4 -
> (strlen(filename) % 4); -
> -			new_entry_byte_reqd = strlen(filename) +
> -			    sizeof(struct ext2_dirent) +
> padding_factor;
> -			padding_factor = 0;
> -			/*
> -			 * update last directory entry length to its
> -			 * length because we are creating new
> directory
> -			 * entry
> -			 */
> -			if (dir->namelen % 4 != 0)
> -				padding_factor = 4 - (dir->namelen %
> 4); 
> -			last_entry_dirlen = dir->namelen +
> -			    sizeof(struct ext2_dirent) +
> padding_factor;
> -			if ((fs->blksz - totalbytes -
> last_entry_dirlen) <
> -				new_entry_byte_reqd) {
> -				printf("Last Block Full:Allocate new
> block\n");
> +			/* check if new entry fits */
> +			if ((used_len + new_entry_byte_reqd) <=
> +			    le16_to_cpu(dir->direntlen)) {
> +				dir->direntlen =
> cpu_to_le16(used_len);
> +				break;
> +			} else {
> +				if (blk_idx > 0) {
> +					printf("Block full, trying
> previous\n");
> +					blk_idx--;
> +					goto restart_read;
> +				}
> +				printf("All blocks full: Allocate
> new\n"); 
>  				if
> (le32_to_cpu(g_parent_inode->flags) & EXT4_EXTENTS_FL) {
>  					printf("Directory uses
> extents\n"); goto fail;
>  				}
> -				if (direct_blk_idx ==
> INDIRECT_BLOCKS - 1) {
> +				if (directory_blocks >=
> INDIRECT_BLOCKS) { printf("Directory exceeds limit\n");
>  					goto fail;
>  				}
> @@ -465,7 +450,8 @@ restart:
>  					goto fail;
>  				}
>  				put_ext4((uint64_t)new_blk_no *
> fs->blksz, zero_buffer, fs->blksz);
> -
> g_parent_inode->b.blocks.dir_blocks[direct_blk_idx] =
> +				g_parent_inode->b.blocks.
> +					dir_blocks[directory_blocks]
> = cpu_to_le32(new_blk_no);
>  
>  				new_size =
> le32_to_cpu(g_parent_inode->size); @@ -482,8 +468,6 @@ restart:
>  					goto fail;
>  				goto restart;
>  			}
> -			dir->direntlen =
> cpu_to_le16(last_entry_dirlen);
> -			break;
>  		}
>  
>  		templength = le16_to_cpu(dir->direntlen);

Reviewed-by: Lukasz Majewski <l.majewski at samsung.com>

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group