Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-linus-1

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6: (9356 commits)
  [media] rc: update for bitop name changes
  fs: simplify iget & friends
  fs: pull inode->i_lock up out of writeback_single_inode
  fs: rename inode_lock to inode_hash_lock
  fs: move i_wb_list out from under inode_lock
  fs: move i_sb_list out from under inode_lock
  fs: remove inode_lock from iput_final and prune_icache
  fs: Lock the inode LRU list separately
  fs: factor inode disposal
  fs: protect inode->i_state with inode->i_lock
  lib, arch: add filter argument to show_mem and fix private implementations
  SLUB: Write to per cpu data when allocating it
  slub: Fix debugobjects with lockless fastpath
  autofs4: Do not potentially dereference NULL pointer returned by fget() in autofs_dev_ioctl_setpipefd()
  autofs4 - remove autofs4_lock
  autofs4 - fix d_manage() return on rcu-walk
  autofs4 - fix autofs4_expire_indirect() traversal
  autofs4 - fix dentry leak in autofs4_expire_direct()
  autofs4 - reinstate last used update on access
  vfs - check non-mountpoint dentry might block in __follow_mount_rcu()
  ...

NOTE!

This merge commit was created to fix compilation error. The block
tree was merged upstream and removed the 'elv_queue_empty()'
function which the new 'mtdswap' driver is using. So a simple
merge of the mtd tree with upstream does not compile. And the
mtd tree has already be published, so re-basing it is not an option.

To fix this unfortunate situation, I had to merge upstream into the
mtd-2.6.git tree without committing, put the fixup patch on top of
this, and then commit this. The result is that we do not have commits
which do not compile.

In other words, this merge commit "merges" 3 things: the MTD tree, the
upstream tree, and the fixup patch.

1 files changed, 326 insertions, 22 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index ddc81a06edb..215a3ce6106 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -23,6 +23,129 @@
  * P2M_PER_PAGE depends on the architecture, as a mfn is always
  * unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
  * 512 and 1024 entries respectively. 
+ *
+ * In short, these structures contain the Machine Frame Number (MFN) of the PFN.
+ *
+ * However not all entries are filled with MFNs. Specifically for all other
+ * leaf entries, or for the top  root, or middle one, for which there is a void
+ * entry, we assume it is  "missing". So (for example)
+ *  pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
+ *
+ * We also have the possibility of setting 1-1 mappings on certain regions, so
+ * that:
+ *  pfn_to_mfn(0xc0000)=0xc0000
+ *
+ * The benefit of this is, that we can assume for non-RAM regions (think
+ * PCI BARs, or ACPI spaces), we can create mappings easily b/c we
+ * get the PFN value to match the MFN.
+ *
+ * For this to work efficiently we have one new page p2m_identity and
+ * allocate (via reserved_brk) any other pages we need to cover the sides
+ * (1GB or 4MB boundary violations). All entries in p2m_identity are set to
+ * INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
+ * no other fancy value).
+ *
+ * On lookup we spot that the entry points to p2m_identity and return the
+ * identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
+ * If the entry points to an allocated page, we just proceed as before and
+ * return the PFN.  If the PFN has IDENTITY_FRAME_BIT set we unmask that in
+ * appropriate functions (pfn_to_mfn).
+ *
+ * The reason for having the IDENTITY_FRAME_BIT instead of just returning the
+ * PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
+ * non-identity pfn. To protect ourselves against we elect to set (and get) the
+ * IDENTITY_FRAME_BIT on all identity mapped PFNs.
+ *
+ * This simplistic diagram is used to explain the more subtle piece of code.
+ * There is also a digram of the P2M at the end that can help.
+ * Imagine your E820 looking as so:
+ *
+ *                    1GB                                           2GB
+ * /-------------------+---------\/----\         /----------\    /---+-----\
+ * | System RAM        | Sys RAM ||ACPI|         | reserved |    | Sys RAM |
+ * \-------------------+---------/\----/         \----------/    \---+-----/
+ *                               ^- 1029MB                       ^- 2001MB
+ *
+ * [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
+ *  2048MB = 524288 (0x80000)]
+ *
+ * And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
+ * is actually not present (would have to kick the balloon driver to put it in).
+ *
+ * When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
+ * Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
+ * of the PFN and the end PFN (263424 and 512256 respectively). The first step
+ * is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
+ * covers 512^2 of page estate (1GB) and in case the start or end PFN is not
+ * aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn
+ * to end pfn.  We reserve_brk top leaf pages if they are missing (means they
+ * point to p2m_mid_missing).
+ *
+ * With the E820 example above, 263424 is not 1GB aligned so we allocate a
+ * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
+ * Each entry in the allocate page is "missing" (points to p2m_missing).
+ *
+ * Next stage is to determine if we need to do a more granular boundary check
+ * on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
+ * We check if the start pfn and end pfn violate that boundary check, and if
+ * so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
+ * granularity of setting which PFNs are missing and which ones are identity.
+ * In our example 263424 and 512256 both fail the check so we reserve_brk two
+ * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
+ * values) and assign them to p2m[1][2] and p2m[1][488] respectively.
+ *
+ * At this point we would at minimum reserve_brk one page, but could be up to
+ * three. Each call to set_phys_range_identity has at maximum a three page
+ * cost. If we were to query the P2M at this stage, all those entries from
+ * start PFN through end PFN (so 1029MB -> 2001MB) would return
+ * INVALID_P2M_ENTRY ("missing").
+ *
+ * The next step is to walk from the start pfn to the end pfn setting
+ * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
+ * If we find that the middle leaf is pointing to p2m_missing we can swap it
+ * over to p2m_identity - this way covering 4MB (or 2MB) PFN space.  At this
+ * point we do not need to worry about boundary aligment (so no need to
+ * reserve_brk a middle page, figure out which PFNs are "missing" and which
+ * ones are identity), as that has been done earlier.  If we find that the
+ * middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
+ * that page (which covers 512 PFNs) and set the appropriate PFN with
+ * IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
+ * set from p2m[1][2][256->511] and p2m[1][488][0->256] with
+ * IDENTITY_FRAME_BIT set.
+ *
+ * All other regions that are void (or not filled) either point to p2m_missing
+ * (considered missing) or have the default value of INVALID_P2M_ENTRY (also
+ * considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
+ * contain the INVALID_P2M_ENTRY value and are considered "missing."
+ *
+ * This is what the p2m ends up looking (for the E820 above) with this
+ * fabulous drawing:
+ *
+ *    p2m         /--------------\
+ *  /-----\       | &mfn_list[0],|                           /-----------------\
+ *  |  0  |------>| &mfn_list[1],|    /---------------\      | ~0, ~0, ..      |
+ *  |-----|       |  ..., ~0, ~0 |    | ~0, ~0, [x]---+----->| IDENTITY [@256] |
+ *  |  1  |---\   \--------------/    | [p2m_identity]+\     | IDENTITY [@257] |
+ *  |-----|    \                      | [p2m_identity]+\\    | ....            |
+ *  |  2  |--\  \-------------------->|  ...          | \\   \----------------/
+ *  |-----|   \                       \---------------/  \\
+ *  |  3  |\   \                                          \\  p2m_identity
+ *  |-----| \   \-------------------->/---------------\   /-----------------\
+ *  | ..  +->+                        | [p2m_identity]+-->| ~0, ~0, ~0, ... |
+ *  \-----/ /                         | [p2m_identity]+-->| ..., ~0         |
+ *         / /---------------\        | ....          |   \-----------------/
+ *        /  | IDENTITY[@0]  |      /-+-[x], ~0, ~0.. |
+ *       /   | IDENTITY[@256]|<----/  \---------------/
+ *      /    | ~0, ~0, ....  |
+ *     |     \---------------/
+ *     |
+ *     p2m_missing             p2m_missing
+ * /------------------\     /------------\
+ * | [p2m_mid_missing]+---->| ~0, ~0, ~0 |
+ * | [p2m_mid_missing]+---->| ..., ~0    |
+ * \------------------/     \------------/
+ *
+ * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
  */
 
 #include <linux/init.h>
@@ -30,6 +153,7 @@
 #include <linux/list.h>
 #include <linux/hash.h>
 #include <linux/sched.h>
+#include <linux/seq_file.h>
 
 #include <asm/cache.h>
 #include <asm/setup.h>
@@ -59,9 +183,15 @@ static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
 static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
 
+static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
+
 RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
 RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
 
+/* We might hit two boundary violations at the start and end, at max each
+ * boundary violation will require three middle nodes. */
+RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
+
 static inline unsigned p2m_top_index(unsigned long pfn)
 {
 	BUG_ON(pfn >= MAX_P2M_PFN);
@@ -136,7 +266,7 @@ static void p2m_init(unsigned long *p2m)
  * - After resume we're called from within stop_machine, but the mfn
  *   tree should alreay be completely allocated.
  */
-void xen_build_mfn_list_list(void)
+void __ref xen_build_mfn_list_list(void)
 {
 	unsigned long pfn;
 
@@ -221,6 +351,9 @@ void __init xen_build_dynamic_phys_to_machine(void)
 	p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
 	p2m_top_init(p2m_top);
 
+	p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
+	p2m_init(p2m_identity);
+
 	/*
 	 * The domain builder gives us a pre-constructed p2m array in
 	 * mfn_list for all the pages initially given to us, so we just
@@ -241,21 +374,15 @@ void __init xen_build_dynamic_phys_to_machine(void)
 		 * As long as the mfn_list has enough entries to completely
 		 * fill a p2m page, pointing into the array is ok. But if
 		 * not the entries beyond the last pfn will be undefined.
-		 * And guessing that the 'what-ever-there-is' does not take it
-		 * too kindly when changing it to invalid markers, a new page
-		 * is allocated, initialized and filled with the valid part.
 		 */
 		if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
 			unsigned long p2midx;
-			unsigned long *p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
-			p2m_init(p2m);
-
-			for (p2midx = 0; pfn + p2midx < max_pfn; p2midx++) {
-				p2m[p2midx] = mfn_list[pfn + p2midx];
-			}
-			p2m_top[topidx][mididx] = p2m;
-		} else
-			p2m_top[topidx][mididx] = &mfn_list[pfn];
+
+			p2midx = max_pfn % P2M_PER_PAGE;
+			for ( ; p2midx < P2M_PER_PAGE; p2midx++)
+				mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
+		}
+		p2m_top[topidx][mididx] = &mfn_list[pfn];
 	}
 
 	m2p_override_init();
@@ -272,6 +399,14 @@ unsigned long get_phys_to_machine(unsigned long pfn)
 	mididx = p2m_mid_index(pfn);
 	idx = p2m_index(pfn);
 
+	/*
+	 * The INVALID_P2M_ENTRY is filled in both p2m_*identity
+	 * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
+	 * would be wrong.
+	 */
+	if (p2m_top[topidx][mididx] == p2m_identity)
+		return IDENTITY_FRAME(pfn);
+
 	return p2m_top[topidx][mididx][idx];
 }
 EXPORT_SYMBOL_GPL(get_phys_to_machine);
@@ -341,9 +476,11 @@ static bool alloc_p2m(unsigned long pfn)
 			p2m_top_mfn_p[topidx] = mid_mfn;
 	}
 
-	if (p2m_top[topidx][mididx] == p2m_missing) {
+	if (p2m_top[topidx][mididx] == p2m_identity ||
+	    p2m_top[topidx][mididx] == p2m_missing) {
 		/* p2m leaf page is missing */
 		unsigned long *p2m;
+		unsigned long *p2m_orig = p2m_top[topidx][mididx];
 
 		p2m = alloc_p2m_page();
 		if (!p2m)
@@ -351,7 +488,7 @@ static bool alloc_p2m(unsigned long pfn)
 
 		p2m_init(p2m);
 
-		if (cmpxchg(&mid[mididx], p2m_missing, p2m) != p2m_missing)
+		if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
 			free_p2m_page(p2m);
 		else
 			mid_mfn[mididx] = virt_to_mfn(p2m);
@@ -360,11 +497,91 @@ static bool alloc_p2m(unsigned long pfn)
 	return true;
 }
 
+bool __early_alloc_p2m(unsigned long pfn)
+{
+	unsigned topidx, mididx, idx;
+
+	topidx = p2m_top_index(pfn);
+	mididx = p2m_mid_index(pfn);
+	idx = p2m_index(pfn);
+
+	/* Pfff.. No boundary cross-over, lets get out. */
+	if (!idx)
+		return false;
+
+	WARN(p2m_top[topidx][mididx] == p2m_identity,
+		"P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
+		topidx, mididx);
+
+	/*
+	 * Could be done by xen_build_dynamic_phys_to_machine..
+	 */
+	if (p2m_top[topidx][mididx] != p2m_missing)
+		return false;
+
+	/* Boundary cross-over for the edges: */
+	if (idx) {
+		unsigned long *p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
+
+		p2m_init(p2m);
+
+		p2m_top[topidx][mididx] = p2m;
+
+	}
+	return idx != 0;
+}
+unsigned long set_phys_range_identity(unsigned long pfn_s,
+				      unsigned long pfn_e)
+{
+	unsigned long pfn;
+
+	if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
+		return 0;
+
+	if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
+		return pfn_e - pfn_s;
+
+	if (pfn_s > pfn_e)
+		return 0;
+
+	for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
+		pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
+		pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
+	{
+		unsigned topidx = p2m_top_index(pfn);
+		if (p2m_top[topidx] == p2m_mid_missing) {
+			unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
+
+			p2m_mid_init(mid);
+
+			p2m_top[topidx] = mid;
+		}
+	}
+
+	__early_alloc_p2m(pfn_s);
+	__early_alloc_p2m(pfn_e);
+
+	for (pfn = pfn_s; pfn < pfn_e; pfn++)
+		if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
+			break;
+
+	if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
+		"Identity mapping failed. We are %ld short of 1-1 mappings!\n",
+		(pfn_e - pfn_s) - (pfn - pfn_s)))
+		printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
+
+	return pfn - pfn_s;
+}
+
 /* Try to install p2m mapping; fail if intermediate bits missing */
 bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 {
 	unsigned topidx, mididx, idx;
 
+	if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
+		BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+		return true;
+	}
 	if (unlikely(pfn >= MAX_P2M_PFN)) {
 		BUG_ON(mfn != INVALID_P2M_ENTRY);
 		return true;
@@ -374,6 +591,21 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 	mididx = p2m_mid_index(pfn);
 	idx = p2m_index(pfn);
 
+	/* For sparse holes were the p2m leaf has real PFN along with
+	 * PCI holes, stick in the PFN as the MFN value.
+	 */
+	if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
+		if (p2m_top[topidx][mididx] == p2m_identity)
+			return true;
+
+		/* Swap over from MISSING to IDENTITY if needed. */
+		if (p2m_top[topidx][mididx] == p2m_missing) {
+			WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
+				p2m_identity) != p2m_missing);
+			return true;
+		}
+	}
+
 	if (p2m_top[topidx][mididx] == p2m_missing)
 		return mfn == INVALID_P2M_ENTRY;
 
@@ -384,11 +616,6 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 
 bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 {
-	if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
-		BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
-		return true;
-	}
-
 	if (unlikely(!__set_phys_to_machine(pfn, mfn)))  {
 		if (!alloc_p2m(pfn))
 			return false;
@@ -427,7 +654,7 @@ int m2p_add_override(unsigned long mfn, struct page *page)
 {
 	unsigned long flags;
 	unsigned long pfn;
-	unsigned long address;
+	unsigned long uninitialized_var(address);
 	unsigned level;
 	pte_t *ptep = NULL;
 
@@ -461,7 +688,7 @@ int m2p_remove_override(struct page *page)
 	unsigned long flags;
 	unsigned long mfn;
 	unsigned long pfn;
-	unsigned long address;
+	unsigned long uninitialized_var(address);
 	unsigned level;
 	pte_t *ptep = NULL;
 
@@ -526,3 +753,80 @@ unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
 	return ret;
 }
 EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
+
+#ifdef CONFIG_XEN_DEBUG_FS
+
+int p2m_dump_show(struct seq_file *m, void *v)
+{
+	static const char * const level_name[] = { "top", "middle",
+						"entry", "abnormal" };
+	static const char * const type_name[] = { "identity", "missing",
+						"pfn", "abnormal"};
+#define TYPE_IDENTITY 0
+#define TYPE_MISSING 1
+#define TYPE_PFN 2
+#define TYPE_UNKNOWN 3
+	unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
+	unsigned int uninitialized_var(prev_level);
+	unsigned int uninitialized_var(prev_type);
+
+	if (!p2m_top)
+		return 0;
+
+	for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
+		unsigned topidx = p2m_top_index(pfn);
+		unsigned mididx = p2m_mid_index(pfn);
+		unsigned idx = p2m_index(pfn);
+		unsigned lvl, type;
+
+		lvl = 4;
+		type = TYPE_UNKNOWN;
+		if (p2m_top[topidx] == p2m_mid_missing) {
+			lvl = 0; type = TYPE_MISSING;
+		} else if (p2m_top[topidx] == NULL) {
+			lvl = 0; type = TYPE_UNKNOWN;
+		} else if (p2m_top[topidx][mididx] == NULL) {
+			lvl = 1; type = TYPE_UNKNOWN;
+		} else if (p2m_top[topidx][mididx] == p2m_identity) {
+			lvl = 1; type = TYPE_IDENTITY;
+		} else if (p2m_top[topidx][mididx] == p2m_missing) {
+			lvl = 1; type = TYPE_MISSING;
+		} else if (p2m_top[topidx][mididx][idx] == 0) {
+			lvl = 2; type = TYPE_UNKNOWN;
+		} else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
+			lvl = 2; type = TYPE_IDENTITY;
+		} else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
+			lvl = 2; type = TYPE_MISSING;
+		} else if (p2m_top[topidx][mididx][idx] == pfn) {
+			lvl = 2; type = TYPE_PFN;
+		} else if (p2m_top[topidx][mididx][idx] != pfn) {
+			lvl = 2; type = TYPE_PFN;
+		}
+		if (pfn == 0) {
+			prev_level = lvl;
+			prev_type = type;
+		}
+		if (pfn == MAX_DOMAIN_PAGES-1) {
+			lvl = 3;
+			type = TYPE_UNKNOWN;
+		}
+		if (prev_type != type) {
+			seq_printf(m, " [0x%lx->0x%lx] %s\n",
+				prev_pfn_type, pfn, type_name[prev_type]);
+			prev_pfn_type = pfn;
+			prev_type = type;
+		}
+		if (prev_level != lvl) {
+			seq_printf(m, " [0x%lx->0x%lx] level %s\n",
+				prev_pfn_level, pfn, level_name[prev_level]);
+			prev_pfn_level = pfn;
+			prev_level = lvl;
+		}
+	}
+	return 0;
+#undef TYPE_IDENTITY
+#undef TYPE_MISSING
+#undef TYPE_PFN
+#undef TYPE_UNKNOWN
+}
+#endif