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ext2: support creation of sparse files

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Matheus
2025-10-03 19:28:59 -03:00
parent 1065dd53b9
commit 7669af39ea
1 changed files with 52 additions and 13 deletions
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kernel-src/fs/ext2.c
+52 -13
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@@ -485,6 +485,10 @@ static int getinodeblock(ext2fs_t *fs, ext2node_t *node, uintmax_t index, blockp
// first singly indirect block
if (singly == 0) {
if (node->inode.singlypointer == 0) {
*block = 0;
return 0;
}
size_t readc;
return vfs_read(fs->backing, block, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, node->inode.singlypointer) + singlyoffset, &readc, 0);
}
@@ -496,11 +500,20 @@ static int getinodeblock(ext2fs_t *fs, ext2node_t *node, uintmax_t index, blockp
// first doubly indirect block
if (doubly == 0) {
if (node->inode.doublypointer == 0) {
*block = 0;
return 0;
}
size_t readc;
blockptr_t singlyptr;
int e = vfs_read(fs->backing, &singlyptr, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, node->inode.doublypointer) + doublyoffset, &readc, 0);
if (e)
return e;
if (singlyptr == 0) {
*block = 0;
return 0;
}
return vfs_read(fs->backing, block, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, singlyptr) + singlyoffset, &readc, 0);
}
@@ -512,14 +525,30 @@ static int getinodeblock(ext2fs_t *fs, ext2node_t *node, uintmax_t index, blockp
size_t readc;
blockptr_t doublyptr;
blockptr_t singlyptr;
if (node->inode.triplypointer == 0) {
*block = 0;
return 0;
}
int e = vfs_read(fs->backing, &doublyptr, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, node->inode.triplypointer) + triplyoffset, &readc, 0);
if (e)
return e;
if (doublyptr == 0) {
*block = 0;
return 0;
}
e = vfs_read(fs->backing, &singlyptr, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, doublyptr) + doublyoffset, &readc, 0);
if (e)
return e;
if (singlyptr == 0) {
*block = 0;
return 0;
}
return vfs_read(fs->backing, block, sizeof(blockptr_t), BLOCK_GETDISKOFFSET(fs, singlyptr) + singlyoffset, &readc, 0);
}
@@ -724,17 +753,28 @@ static int resizeinode(ext2fs_t *fs, ext2node_t *node, size_t newsize) {
size_t currentblockcount = ROUND_UP(INODE_SIZE(&node->inode), fs->blocksize) / fs->blocksize;
if (newblockcount > currentblockcount) {
// grow
for (int i = currentblockcount; i < newblockcount; ++i) {
uintmax_t newblock;
int e = allocatestructure(fs, &newblock, false);
if (e)
return e;
e = setinodeblock(fs, node, i, newblock);
ASSERT_UNCLEAN(fs, e == 0);
if (e)
return e;
// when growing, we do not allocate any new blocks to use the sparse file feature
// instead, we set specific objects to zero
size_t blocks_in_indirect = BLOCKS_IN_INDIRECT(fs);
size_t doubly_start = blocks_in_indirect + 12 ;
size_t triply_start = blocks_in_indirect * blocks_in_indirect + doubly_start;
// direct?
if (currentblockcount < 12) {
for (int i = currentblockcount; i < min(newblockcount, 12); ++i)
node->inode.directpointer[i] = 0;
}
// singly?
if (currentblockcount <= 12 && newblockcount > 12)
node->inode.singlypointer = 0;
// doubly?
if (newblockcount <= doubly_start && newblockcount > doubly_start)
node->inode.doublypointer = 0;
// triply?
if (newblockcount <= triply_start && newblockcount > triply_start)
node->inode.triplypointer = 0;
} else if (newblockcount < currentblockcount) {
// shrink
for (int i = newblockcount; i < currentblockcount; ++i) {
@@ -902,7 +942,7 @@ static int findindir(ext2fs_t *fs, ext2node_t *node, char *name, int *inode, ext
ext2dent_t *dent = (ext2dent_t *)((uintptr_t)dirbuffer + block_offset);
if (namelen == dent->namelen && dent->inode && strncmp(name, dent->name, dent->namelen) == 0) {
if (namelen == dent->namelen && dent->inode && memcmp(name, dent->name, dent->namelen) == 0) {
inodefound = dent->inode;
if (switchnode) {
dent->inode = switchnode->id;
@@ -1014,7 +1054,7 @@ static int removedent(ext2fs_t *fs, ext2node_t *node, char *name, int *inode) {
dent = (ext2dent_t *)((uintptr_t)dirbuffer + block_offset);
if (namelen == dent->namelen && dent->inode && strncmp(name, dent->name, dent->namelen) == 0) {
if (namelen == dent->namelen && dent->inode && memcmp(name, dent->name, dent->namelen) == 0) {
inodefound = dent->inode;
break;
}
@@ -1262,7 +1302,6 @@ static int ext2_getdents(vnode_t *vnode, dent_t *buffer, size_t count, uintmax_t
return ENOTDIR;
int err = 0;
// XXX loading the whole dir into memory at once isn't the best idea but works for now
void *dirbuffer = alloc(fs->blocksize);
if (dirbuffer == NULL)
return ENOMEM;