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Date: Sat, 7 Apr 2007 23:42:00 -0400 (EDT)
From: "John Anthony Kazos Jr." <jakj@...-k-j.com>
To: aeb@....nl
cc: linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] partitions: Rewrite check_partition to remove necessity
of check_part
From: John Anthony Kazos Jr. <jakj@...-k-j.com>
Removes the entire check_part array and uses the presence of new stub
functions in header files in fs/partitions to call them directly in a list
and let the compiler optimize away any that aren't compiled in. Also fixes
a bug where " unable to read partition table" would never be printed.
Signed-off-by: John Anthony Kazos Jr. <jakj@...-k-j.com>
---
I did this because it seems to be much easier to understand. And even
though the memory used by the array was only sizeof(void*)*n+1 for the
number of partitions configured to be included, that's still unnecessary
usage.
This code also has two warn_unused_result problems, but I don't feel up to
the task of fixing those yet.
Within the old loop, if res < 0, res = 0, and immediately after the loop,
the function returns if res > 0. Therefore, it must be that res == 0 after
the loop. if (!err) is true only if err == 0 so again, res == 0, so if
(!res) is true, and the else condition can never be reached. I
re-interpreted the intent to be "log a message if the partition format is
unrecognized, and log a message if the partition cannot be read but only
if the warning is requested". Judging by the "This is ugly" comment, the
warning is not intended to account for actual I/O errors when reading the
partition-table block, but rather to detect when the partitions are
checked for a device with a medium that has been removed.
--- linux-2.6.20.6-orig/fs/partitions/check.c 2007-04-06 16:02:48.000000000 -0400
+++ linux-2.6.20.6-mod/fs/partitions/check.c 2007-04-07 21:50:22.000000000 -0400
@@ -41,73 +41,6 @@ extern void md_autodetect_dev(dev_t dev)
int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
-static int (*check_part[])(struct parsed_partitions *, struct block_device *) = {
- /*
- * Probe partition formats with tables at disk address 0
- * that also have an ADFS boot block at 0xdc0.
- */
-#ifdef CONFIG_ACORN_PARTITION_ICS
- adfspart_check_ICS,
-#endif
-#ifdef CONFIG_ACORN_PARTITION_POWERTEC
- adfspart_check_POWERTEC,
-#endif
-#ifdef CONFIG_ACORN_PARTITION_EESOX
- adfspart_check_EESOX,
-#endif
-
- /*
- * Now move on to formats that only have partition info at
- * disk address 0xdc0. Since these may also have stale
- * PC/BIOS partition tables, they need to come before
- * the msdos entry.
- */
-#ifdef CONFIG_ACORN_PARTITION_CUMANA
- adfspart_check_CUMANA,
-#endif
-#ifdef CONFIG_ACORN_PARTITION_ADFS
- adfspart_check_ADFS,
-#endif
-
-#ifdef CONFIG_EFI_PARTITION
- efi_partition, /* this must come before msdos */
-#endif
-#ifdef CONFIG_SGI_PARTITION
- sgi_partition,
-#endif
-#ifdef CONFIG_LDM_PARTITION
- ldm_partition, /* this must come before msdos */
-#endif
-#ifdef CONFIG_MSDOS_PARTITION
- msdos_partition,
-#endif
-#ifdef CONFIG_OSF_PARTITION
- osf_partition,
-#endif
-#ifdef CONFIG_SUN_PARTITION
- sun_partition,
-#endif
-#ifdef CONFIG_AMIGA_PARTITION
- amiga_partition,
-#endif
-#ifdef CONFIG_ATARI_PARTITION
- atari_partition,
-#endif
-#ifdef CONFIG_MAC_PARTITION
- mac_partition,
-#endif
-#ifdef CONFIG_ULTRIX_PARTITION
- ultrix_partition,
-#endif
-#ifdef CONFIG_IBM_PARTITION
- ibm_partition,
-#endif
-#ifdef CONFIG_KARMA_PARTITION
- karma_partition,
-#endif
- NULL
-};
-
/*
* disk_name() is used by partition check code and the genhd driver.
* It formats the devicename of the indicated disk into
@@ -149,11 +82,125 @@ const char *__bdevname(dev_t dev, char *
EXPORT_SYMBOL(__bdevname);
+static int
+check_succeeded(int res, struct parsed_partitions *state, int *err)
+{
+ if (res < 0) {
+ /* We have hit an I/O error which we don't report now.
+ * But record it, and let the others do their job.
+ */
+ *err = res;
+ res = 0;
+ }
+
+ if (!res) {
+ memset(state->parts, 0, sizeof(state->parts));
+ }
+
+ return res;
+}
+
+static struct parsed_partitions *
+do_check_list(struct parsed_partitions *state, struct block_device *bdev)
+{
+ int err;
+
+ err = 0;
+
+ /*
+ * Probe partition formats with tables at disk address 0
+ * that also have an ADFS boot block at 0xdc0.
+ */
+ if (check_succeeded(adfspart_check_ICS(state, bdev), state, &err)) {
+ return state;
+ }
+ if (check_succeeded(adfspart_check_POWERTEC(state, bdev), state, &err)) {
+ return state;
+ }
+ if (check_succeeded(adfspart_check_EESOX(state, bdev), state, &err)) {
+ return state;
+ }
+
+ /*
+ * Now move on to formats that only have partition info at
+ * disk address 0xdc0. Since these may also have stale
+ * PC/BIOS partition tables, they need to come before
+ * the msdos entry.
+ */
+ if (check_succeeded(adfspart_check_CUMANA(state, bdev), state, &err)) {
+ return state;
+ }
+ if (check_succeeded(adfspart_check_ADFS(state, bdev), state, &err)) {
+ return state;
+ }
+
+ /* this must come before msdos */
+ if (check_succeeded(efi_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(sgi_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ /* this must come before msdos */
+ if (check_succeeded(ldm_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(msdos_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(osf_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(sun_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(amiga_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(atari_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(mac_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(ultrix_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(ibm_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ if (check_succeeded(karma_partition(state, bdev), state, &err)) {
+ return state;
+ }
+
+ kfree(state);
+
+ if (err) {
+ if (warn_no_part) {
+ printk(" unable to read partition table\n");
+ }
+ } else {
+ printk(" unknown partition table\n");
+ }
+
+ return ERR_PTR(err);
+}
+
static struct parsed_partitions *
check_partition(struct gendisk *hd, struct block_device *bdev)
{
struct parsed_partitions *state;
- int i, res, err;
state = kmalloc(sizeof(struct parsed_partitions), GFP_KERNEL);
if (!state)
@@ -165,30 +212,8 @@ check_partition(struct gendisk *hd, stru
sprintf(state->name, "p");
state->limit = hd->minors;
- i = res = err = 0;
- while (!res && check_part[i]) {
- memset(&state->parts, 0, sizeof(state->parts));
- res = check_part[i++](state, bdev);
- if (res < 0) {
- /* We have hit an I/O error which we don't report now.
- * But record it, and let the others do their job.
- */
- err = res;
- res = 0;
- }
- }
- if (res > 0)
- return state;
- if (!err)
- /* The partition is unrecognized. So report I/O errors if there were any */
- res = err;
- if (!res)
- printk(" unknown partition table\n");
- else if (warn_no_part)
- printk(" unable to read partition table\n");
- kfree(state);
- return ERR_PTR(res);
+ return do_check_list(state, bdev);
}
/*
-
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