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SubjectREPOST: Some Cleanup Fixes for the Ramdisk Stuff
Sorry if you have seen this before -- I haven't seen it from linux-kernel,
so I assume it went into a black hole somewhere.

The attached patch makes some mostly cosmetic corrections to the recent
ramdisk patch. This is against pre-2.3.35-4, although it should be the
same against pre-2.3.35-6.

1. Clean up the commentary somewhat.

2. Remove two non-zero values from memset() calls that were there for
debugging.

3. In the case of no buffers available, return a failure reply to the
caller, rather than performing a BUG() call. This doesn't change
anything as far as out-of-memory conditions are concerned; only the
reporting.

=====================================================================
--- linux/drivers/block/rd.c.orig Sun Dec 26 20:58:01 1999
+++ linux/drivers/block/rd.c Sun Dec 26 21:06:10 1999
@@ -217,24 +217,23 @@
}

/*
- * This has become somewhat more complicated with the addition of
- * the page cache. The problem is that in some cases the furnished
+ * There is a problem here in that in some cases the furnished
* buffer is "real", i.e., part of the existing ramdisk, while in
* others it is "unreal", e.g., part of a page. In the first case
* not much needs to be done, while in the second, some kind of
* transfer is needed.
*
- * The two cases are distinguished here by checking whether the
- * real buffer is already in the buffer cache, and whether it is
- * the same as the one supplied.
+ * The two cases are distinguished by checking whether the real
+ * buffer is already in the buffer cache, and whether it matches
+ * the one supplied.
*
* There are three cases with read/write to consider:
*
- * 1. Supplied buffer matched one in the buffer cache:
- * Read - Clear the buffer, as it wasn't already valid.
+ * 1. Supplied buffer matched the one in the buffer cache:
+ * Read - Clear the buffer, as it wasn't previously valid.
* Write - Mark the buffer as "Protected".
*
- * 2. Supplied buffer mismatched one in the buffer cache:
+ * 2. Supplied buffer mismatched the one in the buffer cache:
* Read - Copy the data from the buffer cache entry.
* Write - Copy the data to the buffer cache entry.
*
@@ -243,19 +242,13 @@
* one.
* Write - Create a real buffer, copy the data to it, and mark
* it as "Protected".
- *
- * NOTE: There seems to be some schizophrenia here - the logic
- * using "len" seems to assume arbitrary request lengths, while
- * the "protect" logic assumes a single buffer cache entry.
- * This seems to be left over from the ancient contiguous ramdisk
- * logic.
*/

sbh = CURRENT->bh;
rbh = get_hash_table(sbh->b_dev, sbh->b_blocknr, sbh->b_size);
if (sbh == rbh) {
if (CURRENT->cmd == READ)
- memset(CURRENT->buffer, 1, len);
+ memset(CURRENT->buffer, 0, len);
} else if (rbh) {
if (CURRENT->cmd == READ)
memcpy(CURRENT->buffer, rbh->b_data, rbh->b_size);
@@ -263,14 +256,18 @@
memcpy(rbh->b_data, CURRENT->buffer, rbh->b_size);
} else { /* !rbh */
if (CURRENT->cmd == READ)
- memset(sbh->b_data, 2, len);
+ memset(sbh->b_data, 0, len);
else {
rbh = getblk(sbh->b_dev, sbh->b_blocknr, sbh->b_size);
if (rbh)
memcpy(rbh->b_data, CURRENT->buffer,
rbh->b_size);
- else
- BUG(); /* No buffer, what to do here? */
+ else {
+ printk(KERN_ERR "RAMDISK: "
+ "could not allocate buffer\n");
+ end_request(0);
+ goto repeat;
+ }
}
}
if (rbh) {
=====================================================================
--
B. D. Elliott bde@nwlink.com (Seattle)
-
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