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Add ext4 extent support

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This commit is contained in:
Matteo Semenzato 2020-09-21 13:09:00 +02:00
parent 4927abcfaf
commit 81faf039af
1 changed files with 87 additions and 4 deletions
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91
stage2/fs/ext2.c
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@ -16,6 +16,9 @@
#define EXT2_IF_INLINE_DATA 0x8000
#define EXT2_IF_ENCRYPT 0x10000
/* Ext4 flags */
#define EXT4_EXTENTS_FLAG 0x80000
#define EXT2_S_MAGIC 0xEF53
/* Superblock Fields */
@ -90,6 +93,28 @@ struct ext2_dir_entry {
uint8_t type;
} __attribute__((packed));
struct ext4_extent_header {
uint16_t magic;
uint16_t entries;
uint16_t max;
uint16_t depth;
uint16_t generation;
} __attribute__((packed));
struct ext4_extent {
uint32_t block;
uint16_t len;
uint16_t start_hi;
uint32_t start;
} __attribute__((packed));
struct ext4_extent_idx {
uint32_t block;
uint32_t leaf;
uint16_t leaf_hi;
uint16_t empty;
} __attribute__((packed));
static int inode_read(void *buf, uint64_t loc, uint64_t count,
uint64_t block_size, struct ext2_inode *inode,
uint64_t drive, struct part *part);
@ -212,6 +237,38 @@ int ext2_read(struct ext2_file_handle *file, void *buf, uint64_t loc, uint64_t c
file->drive, &file->part);
}
static struct ext4_extent_header* ext4_find_leaf(struct ext4_extent_header* ext_block, uint32_t read_block, uint64_t block_size, uint64_t drive, struct part *part) {
struct ext4_extent_idx* index;
void* buf = NULL;
while (1) {
index = (struct ext4_extent_idx*)((size_t)ext_block + 12);
#define EXT4_EXT_MAGIC 0xf30a
if (ext_block->magic != EXT4_EXT_MAGIC)
panic("invalid extent magic");
if (ext_block->depth == 0) {
return ext_block;
}
int i;
for (i = 0; i < ext_block->entries; i++) {
if(read_block < index[i].block)
break;
}
if (--i < 0)
panic("extent not found");
uint64_t block = (index[i].leaf_hi << 32) | index[i].leaf;
if(!buf)
buf = balloc(block_size);
read_partition(drive, part, buf, (block * block_size), block_size);
ext_block = buf;
}
}
static int inode_read(void *buf, uint64_t loc, uint64_t count,
uint64_t block_size, struct ext2_inode *inode,
uint64_t drive, struct part *part) {
@ -225,7 +282,35 @@ static int inode_read(void *buf, uint64_t loc, uint64_t count,
uint32_t block_index;
if (block < 12) {
if (inode->i_flags & EXT4_EXTENTS_FLAG) {
struct ext4_extent_header *leaf;
struct ext4_extent *ext;
int i;
leaf = ext4_find_leaf((struct ext4_extent_header*)inode->i_blocks, block, block_size, drive, part);
if (!leaf)
panic("invalid extent");
ext = (struct ext4_extent*)((size_t)leaf + 12);
for (i = 0; i < leaf->entries; i++) {
if (block < ext[i].block) {
break;
}
}
if (--i >= 0) {
block -= ext[i].block;
if (block >= ext[i].len) {
panic("block longer than extent");
} else {
uint64_t start = (ext[i].start_hi << 32) + ext[i].start;
block_index = start + block;
}
} else {
panic("extent for block not found");
}
} else if (block < 12) {
// Direct block
block_index = inode->i_blocks[block];
} else {
@ -286,11 +371,9 @@ int ext2_check_signature(int drive, int partition) {
return 1;
if (sb.s_feature_incompat & EXT2_IF_COMPRESSION ||
sb.s_feature_incompat & EXT2_IF_EXTENTS ||
sb.s_feature_incompat & EXT2_IF_INLINE_DATA ||
sb.s_feature_incompat & EXT2_IF_64BIT ||
sb.s_feature_incompat & EXT2_IF_ENCRYPT)
panic("EXT2: filesystem has unsupported features");
panic("EXT2: filesystem has unsupported features %x", sb.s_feature_incompat);
return 1;
}