Imagelibrary/littlefs
1
0
Fork 1
mirror of https://github.com/littlefs-project/littlefs.git synced 2025-11-16 12:34:34 +00:00
Code Issues Packages Projects Releases Wiki Activity

Added full dir list and rudimentary block allocator

Browse Source 
In writing the initial allocator, I ran into the rather
difficult problem of trying to iterate through the entire
filesystem cheaply and with only constant memory consumption
(which prohibits recursive functions).

The solution was to simply thread all directory blocks onto a
massive linked-list that spans the entire filesystem.

With the linked-list it was easy to create a traverse function
for all blocks in use on the filesystem (which has potential
for other utility), and add the rudimentary block allocator
using a bit-vector.

While the linked-list may add complexity (especially where
needing to maintain atomic operations), the linked-list helps
simplify what is currently the most expensive operation in
the filesystem, with no cost to space (the linked-list can
reuse the pointers used for chained directory blocks).
This commit is contained in:
Christopher Haster
2017-04-01 10:44:17 -05:00
parent ca01b72a35
commit 8a674524fc
7 changed files with 502 additions and 60 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
lfs.h
View File

@@ -96,11 +96,6 @@ typedef struct lfs_dir {
uint32_t rev;
lfs_size_t size;
lfs_block_t tail[2];
struct lfs_disk_free {
uint32_t begin;
uint32_t end;
} free;
} d;
} lfs_dir_t;
@@ -118,18 +113,23 @@ typedef struct lfs_superblock {
// Little filesystem type
typedef struct lfs {
lfs_bd_t *bd;
const struct lfs_bd_ops *bd_ops;
lfs_block_t root[2];
lfs_block_t cwd[2];
struct lfs_disk_free free;
lfs_size_t read_size; // size of read
lfs_size_t prog_size; // size of program
lfs_size_t block_size; // size of erase (block size)
lfs_size_t block_count; // number of erasable blocks
lfs_size_t words; // number of 32-bit words that can fit in a block
lfs_bd_t *bd;
const struct lfs_bd_ops *bd_ops;
lfs_block_t root[2];
lfs_block_t cwd[2];
struct {
lfs_block_t begin;
lfs_block_t end;
} free;
uint32_t lookahead[LFS_CFG_LOOKAHEAD/32];
} lfs_t;
// Functions
@@ -137,6 +137,8 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *config);
int lfs_mount(lfs_t *lfs, const struct lfs_config *config);
int lfs_unmount(lfs_t *lfs);
int lfs_remove(lfs_t *lfs, const char *path);
int lfs_mkdir(lfs_t *lfs, const char *path);
int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path);
int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir);