linux-next: build failure after merge of the xarray tree

From: Stephen Rothwell
Date: Sun Jun 17 2018 - 23:27:22 EST

Hi all,

After merging the xarray tree, today's linux-next build (powerpc
ppc64_defconfig) failed like this:

In file included from arch/powerpc/include/asm/bug.h:128:0,
from include/linux/bug.h:5,
from arch/powerpc/include/asm/cmpxchg.h:9,
from arch/powerpc/include/asm/atomic.h:11,
from include/linux/atomic.h:5,
from fs/dax.c:17:
fs/dax.c: In function 'dax_lock_page':
fs/dax.c:392:21: error: implicit declaration of function 'radix_tree_exceptional_entry'; did you mean 'radix_tree_exception'? [-Werror=implicit-function-declaration]
WARN_ON_ONCE(!radix_tree_exceptional_entry(entry))) {
^
include/asm-generic/bug.h:69:25: note: in definition of macro 'WARN_ON_ONCE'
int __ret_warn_on = !!(condition); \
^~~~~~~~~
fs/dax.c:395:15: error: implicit declaration of function 'slot_locked'; did you mean 'iget_locked'? [-Werror=implicit-function-declaration]
} else if (!slot_locked(mapping, slot)) {
^~~~~~~~~~~
iget_locked
fs/dax.c:396:4: error: implicit declaration of function 'lock_slot'; did you mean 'local_set'? [-Werror=implicit-function-declaration]
lock_slot(mapping, slot);
^~~~~~~~~
local_set
fs/dax.c:402:28: error: passing argument 1 of 'dax_entry_waitqueue' from incompatible pointer type [-Werror=incompatible-pointer-types]
wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
^~~~~~~
fs/dax.c:152:27: note: expected 'struct xa_state *' but argument is of type 'struct address_space *'
static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
^~~~~~~~~~~~~~~~~~~
fs/dax.c:402:37: warning: passing argument 2 of 'dax_entry_waitqueue' makes pointer from integer without a cast [-Wint-conversion]
wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
^~~~~
fs/dax.c:152:27: note: expected 'void *' but argument is of type 'long unsigned int'
static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
^~~~~~~~~~~~~~~~~~~
fs/dax.c:402:8: error: too many arguments to function 'dax_entry_waitqueue'
wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
^~~~~~~~~~~~~~~~~~~
fs/dax.c:152:27: note: declared here
static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
^~~~~~~~~~~~~~~~~~~
fs/dax.c: In function 'dax_unlock_page':
fs/dax.c:424:2: error: implicit declaration of function 'dax_unlock_mapping_entry'; did you mean 'dax_delete_mapping_entry'? [-Werror=implicit-function-declaration]
dax_unlock_mapping_entry(mapping, page->index);
^~~~~~~~~~~~~~~~~~~~~~~~
dax_delete_mapping_entry

Caused by commits in the xarray tree interacting with commit

9b3d53936caa ("filesystem-dax: Introduce dax_lock_page()")

from the nvdimm tree.

Willy thanks for the heads up about this.

I have applied the following merge fix patch (taken from the diff between
the -next tree at this point and the xarray-20180615 branch from the
xarray tree) for today.

From: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Date: Mon, 18 Jun 2018 13:17:15 +1000
Subject: [PATCH] filesystem-dax: fixups for xaarray changes

Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
---
fs/dax.c | 75 +++++++++++++++++++++++++-------------------------------
1 file changed, 34 insertions(+), 41 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 579088945add..91f7bce6ce64 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -350,78 +350,71 @@ static struct page *dax_busy_page(void *entry)

struct page *dax_lock_page(unsigned long pfn)
{
- pgoff_t index;
- struct inode *inode;
- wait_queue_head_t *wq;
- void *entry = NULL, **slot;
+ struct page *page = pfn_to_page(pfn);
+ XA_STATE(xas, NULL, 0);
+ void *entry;
struct address_space *mapping;
- struct wait_exceptional_entry_queue ewait;
- struct page *ret = NULL, *page = pfn_to_page(pfn);

- rcu_read_lock();
for (;;) {
+ rcu_read_lock();
mapping = READ_ONCE(page->mapping);

- if (!mapping || !IS_DAX(mapping->host))
+ if (!mapping || !IS_DAX(mapping->host)) {
+ page = NULL;
break;
+ }

/*
* In the device-dax case there's no need to lock, a
* struct dev_pagemap pin is sufficient to keep the
* inode alive.
*/
- inode = mapping->host;
- if (S_ISCHR(inode->i_mode)) {
- ret = page;
+ if (S_ISCHR(mapping->host->i_mode))
break;
- }

- xa_lock_irq(&mapping->i_pages);
+ xas.xa = &mapping->i_pages;
+ xas_lock_irq(&xas);
+ rcu_read_unlock();
if (mapping != page->mapping) {
xa_unlock_irq(&mapping->i_pages);
continue;
}
- index = page->index;
-
- init_wait(&ewait.wait);
- ewait.wait.func = wake_exceptional_entry_func;
-
- entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
- &slot);
- if (!entry ||
- WARN_ON_ONCE(!radix_tree_exceptional_entry(entry))) {
- xa_unlock_irq(&mapping->i_pages);
- break;
- } else if (!slot_locked(mapping, slot)) {
- lock_slot(mapping, slot);
- ret = page;
- xa_unlock_irq(&mapping->i_pages);
- break;
+ xas_set(&xas, page->index);
+ entry = xas_load(&xas);
+ if (dax_is_locked(entry)) {
+ entry = get_unlocked_entry(&xas);
+ /* Did the page move while we slept? */
+ if (dax_to_pfn(entry) != pfn) {
+ xas_unlock_irq(&xas);
+ continue;
+ }
}
-
- wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
- prepare_to_wait_exclusive(wq, &ewait.wait,
- TASK_UNINTERRUPTIBLE);
- xa_unlock_irq(&mapping->i_pages);
- rcu_read_unlock();
- schedule();
- finish_wait(wq, &ewait.wait);
- rcu_read_lock();
+ dax_lock_entry(&xas, entry);
+ xas_unlock_irq(&xas);
+ goto out;
}
rcu_read_unlock();

+out:
return page;
}

void dax_unlock_page(struct page *page)
{
struct address_space *mapping = page->mapping;
- struct inode *inode = mapping->host;
+ XA_STATE(xas, &mapping->i_pages, page->index);
+ void *entry;

- if (S_ISCHR(inode->i_mode))
+ if (S_ISCHR(mapping->host->i_mode))
return;

- dax_unlock_mapping_entry(mapping, page->index);
+ xas_lock_irq(&xas);
+ entry = xas_load(&xas);
+ BUG_ON(!dax_is_locked(entry));
+ entry = dax_make_page_entry(page, entry);
+ xas_store(&xas, entry);
+ dax_wake_entry(&xas, entry, false);
+ xas_unlock_irq(&xas);
}

/*
--
2.17.1

--
Cheers,
Stephen Rothwell

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