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ext4: Scan all directory blocks for space when inserting a new entry

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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@rwth-aachen.de>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>
This commit is contained in:
Stefan Brüns 2016-09-06 04:36:44 +02:00 committed by Tom Rini
parent b96c3c7292
commit a321abd54f
1 changed files with 30 additions and 44 deletions
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74
fs/ext4/ext4_common.c
View file

@ -370,14 +370,10 @@ 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;
@ -389,6 +385,7 @@ 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) {
@ -401,19 +398,18 @@ 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);
if (first_block_no_of_root <= 0)
goto fail;
status = ext4fs_devread((lbaint_t)first_block_no_of_root
* fs->sect_perblk,
@ -425,42 +421,33 @@ 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;
}
@ -470,7 +457,8 @@ 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);
@ -487,8 +475,6 @@ restart:
goto fail;
goto restart;
}
dir->direntlen = cpu_to_le16(last_entry_dirlen);
break;
}
templength = le16_to_cpu(dir->direntlen);