4 files changed, 88 insertions, 50 deletions

diff --git a/kernel/fs/block.c b/kernel/fs/block.c
index caf97d2..8f9d907 100644
--- a/kernel/fs/block.c
+++ b/kernel/fs/block.c
@@ -1,9 +1,23 @@
+#include <kernel/fd.h>
+#include <kernel/fs.h>
 #include <sys/types.h>
 
-int block_read(void *buf, size_t block) {
-  return -1;
+/*
+ * Minix Major Numbers:
+ *
+ * [0] NULL
+ * [1] /dev/mem
+ * [2] /dev/fdX
+ * [3] /dev/hdX
+ * [4] /dev/ttyX
+ * [5] /dev/tty
+ * [6] /dev/lpX
+ */
+
+void block_read(struct buffer *b) {
+  fd_block_read(b);
 }
 
-int block_write(void *buf, size_t block) {
-  return -1;
+void block_write(struct buffer *b) {
+  b->b_device = 0;
 }
diff --git a/kernel/fs/buffer.c b/kernel/fs/buffer.c
index 7405738..99c3161 100644
--- a/kernel/fs/buffer.c
+++ b/kernel/fs/buffer.c
@@ -1,16 +1,76 @@
+#include <asm/interrupt.h>
+#include <errno.h>
 #include <kernel/con.h>
 #include <kernel/fs.h>
 #include <stdint.h>
 #include <string.h>
 
 /* memory dedicated to the block cache */
+/* TODO: start buffers at kernel end not 512K */
 #define BSTART 0x80000
 #define BEND 0xA0000
 
 static struct buffer *lru;
 static struct buffer *mru;
 
-struct buffer *buffer_get_block(uint16_t device, uint16_t block);
+struct buffer *buffer_get_block(uint16_t device, uint16_t block) {
+  struct buffer **p = &mru;
+  struct buffer *b;
+
+  if(!device)
+    return NULL;
+
+  /* check if the requested block is already in the cache */
+  while(b = *p) {
+    if(b->b_device != device || b->b_block != block)
+      goto next;
+    /* remove the buffer from the list */
+    if(lru == b && b->b_next)   lru = b->b_next;
+    if(b->b_next)               b->b_next->b_prev = b->b_prev;
+    if(b->b_prev)               b->b_prev->b_next = b->b_next;
+    /* put the buffer back at the MRU end of the list */
+    b->b_next = NULL;
+    b->b_prev = mru;
+    if(mru != b)
+      mru->b_next = b;
+    mru = b;
+    cli();
+    /* if the buffer exists but isn't populated. wait on it */
+    if(!b->b_present) {
+      sleep_on(&b->b_wait);
+      printk("[buf] Waiting for buffer %04x:%04x to be populated...\n", b->b_device, b->b_block);
+    }
+    sti();
+    printk("[buf] Fetched block %04x:%04x from cache\n", b->b_device, b->b_block);
+    return b->b_device ? b : NULL;
+next:
+    p = &b->b_prev;
+  }
+
+  /*
+   * otherwise, iterate through the least recently used
+   * buffers, to find a buffer that isn't pending an
+   * I/O operation, and read into it.
+   */
+
+  p = &lru;
+  while(b = *p) {
+    if(b->b_present || !b->b_device)
+      break;
+    p = &(*p)->b_next;
+  }
+
+  if(!b)
+    return NULL;
+
+  b->b_device = device;
+  b->b_block = block;
+  b->b_present = 0;
+  block_read(b);
+  wake_up(&b->b_wait);
+  printk("[buf] Called driver to read block %04x:%04x\n", b->b_device, b->b_block);
+  return b->b_device ? b : NULL;
+}
 
 void buffer_init(void) {
   int c = 0;
@@ -40,43 +100,3 @@ void buffer_init(void) {
 
   printk("[buf] Buffers initialized (0x%x buffers in pool)\n", c);
 }
-
-struct buffer *buffer_get_block(uint16_t device, uint16_t block) {
-  int ret;
-  struct buffer **p = &mru;
-  struct buffer *b;
-
-  /* check if the requested block is already in the cache */
-  while(*p) {
-    if((*p)->b_device == device && (*p)->b_block == block) {
-      /* put the buffer back at the MRU end of the list */
-      (*p)->b_next = NULL;
-      (*p)->b_prev = mru;
-      mru = *p;
-      return *p;
-    }
-    p = &(*p)->b_prev;
-  }
-
-  /* find a buffer at the end of the LRU list */
-  b = lru;
-  lru = lru->b_next;
-  lru->b_prev = NULL;
-  ret = block_read(b->b_data, block);
-  /* abort if we failed to read in the block */
-  if(ret < 0) {
-    /* release the allocated buffer to the pool */
-    lru->b_prev = b;
-    b->b_next = lru;
-    b->b_prev = NULL;
-    lru = b;
-    return NULL;
-  }
-  b->b_device = device;
-  b->b_block = block;
-  /* put the buffer back at the MRU end of the list */
-  b->b_next = NULL;
-  b->b_prev = mru;
-  mru = b;
-  return b;
-}
diff --git a/kernel/fs/fs.c b/kernel/fs/fs.c
index 381f20a..e460a4a 100644
--- a/kernel/fs/fs.c
+++ b/kernel/fs/fs.c
@@ -1,5 +1,6 @@
 #include <errno.h>
 #include <kernel/con.h>
+#include <kernel/fd.h>
 #include <kernel/fs.h>
 #include <kernel/kernel.h>
 #include <kernel/sched.h>
@@ -32,6 +33,7 @@ void fs_init(void) {
   buffer_init();
 
   /* hd_init(); */
+  fd_init();
 
   mount_root();
 }
diff --git a/kernel/fs/mount.c b/kernel/fs/mount.c
index 9cdf49b..e4d3636 100644
--- a/kernel/fs/mount.c
+++ b/kernel/fs/mount.c
@@ -7,15 +7,17 @@ struct super_block sblocks[NRSUPER];
 
 void mount_root(void) {
   int ret;
-  char buf[BLOCK_SIZE];
-  struct super_block *s = (void*) buf;
+  struct buffer *b;
+  struct super_block *s;
 
-  ret = block_read(buf, 1);
-  if(ret < 0) {
+  b = buffer_get_block(1, 1);
+  if(!b) {
     printk("[fs] Failed to read super block\n");
     return;
   }
 
+  s = b->b_data;
+
   if(s->s_magic != SUPER_MAGIC) {
     printk("[fs] Invalid magic number in super block!\n");
     return;
@@ -31,5 +33,5 @@ void mount_root(void) {
   printk("  Max file size: 0x%01x\n", s->s_max_size);
 
   /* copy the super block into the table */
-  memcpy(sblocks, buf, ((unsigned) &s->s_imap - (unsigned) s));
+  memcpy(sblocks, s, ((unsigned) &s->s_imap - (unsigned) s));
 }