[PATCH 04/19] Make effect of PF_FSTRANS to disable __GFP_FS universal.

NeilBrown
2014-04-16T04:25:18Z

Currently both xfs and nfs will handle PF_FSTRANS by disabling
__GFP_FS.

Make this effect global by repurposing memalloc_noio_flags (which
does the same thing for PF_MEMALLOC_NOIO and __GFP_IO) to generally
impost the task flags on a gfp_t.
Due to this repurposing we change the name of memalloc_noio_flags
to gfp_from_current().

As PF_FSTRANS now uniformly removes __GFP_FS we can remove special
code for this from xfs and nfs.

As we can now expect other code to set PF_FSTRANS, its meaning is more
general, so the WARN_ON in xfs_vm_writepage() which checks PF_FSTRANS
is not set is no longer appropriate. PF_FSTRANS may be set for other
reasons than an XFS transaction.

As lockdep cares about __GFP_FS, we need to translate PF_FSTRANS to
__GFP_FS before calling lockdep_alloc_trace() in various places.

Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/nfs/file.c | 3 +--
fs/xfs/kmem.h | 2 --
fs/xfs/xfs_aops.c | 7 -------
include/linux/sched.h | 5 ++++-
mm/page_alloc.c | 3 ++-
mm/slab.c | 2 ++
mm/slob.c | 2 ++
mm/slub.c | 1 +
mm/vmscan.c | 4 ++--
9 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 5bb790a69c71..ed863f52bae7 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -472,8 +472,7 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
/* Only do I/O if gfp is a superset of GFP_KERNEL, and we're not
* doing this memory reclaim for a fs-related allocation.
*/
- if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL &&
- !(current->flags & PF_FSTRANS)) {
+ if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL) {
int how = FLUSH_SYNC;

/* Don't let kswapd deadlock waiting for OOM RPC calls */
diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
index 64db0e53edea..882b86270ebe 100644
--- a/fs/xfs/kmem.h
+++ b/fs/xfs/kmem.h
@@ -50,8 +50,6 @@ kmem_flags_convert(xfs_km_flags_t flags)
lflags = GFP_ATOMIC | __GFP_NOWARN;
} else {
lflags = GFP_KERNEL | __GFP_NOWARN;
- if ((current->flags & PF_FSTRANS) || (flags & KM_NOFS))
- lflags &= ~__GFP_FS;
}

if (flags & KM_ZERO)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index db2cfb067d0b..207a7f86d5d7 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -952,13 +952,6 @@ xfs_vm_writepage(
PF_MEMALLOC))
goto redirty;

- /*
- * Given that we do not allow direct reclaim to call us, we should
- * never be called while in a filesystem transaction.
- */
- if (WARN_ON(current->flags & PF_FSTRANS))
- goto redirty;
-
/* Is this page beyond the end of the file? */
offset = i_size_read(inode);
end_index = offset >> PAGE_CACHE_SHIFT;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 56fa52a0654c..f3291ed33c27 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1860,10 +1860,13 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
#define used_math() tsk_used_math(current)

/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags */
-static inline gfp_t memalloc_noio_flags(gfp_t flags)
+/* __GFP_FS isn't allowed if PF_FSTRANS is set in current->flags */
+static inline gfp_t gfp_from_current(gfp_t flags)
{
if (unlikely(current->flags & PF_MEMALLOC_NOIO))
flags &= ~__GFP_IO;
+ if (unlikely(current->flags & PF_FSTRANS))
+ flags &= ~__GFP_FS;
return flags;
}

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ff8b91aa0b87..5e9225df3447 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2718,6 +2718,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
struct mem_cgroup *memcg = NULL;

gfp_mask &= gfp_allowed_mask;
+ gfp_mask = gfp_from_current(gfp_mask);

lockdep_trace_alloc(gfp_mask);

@@ -2765,7 +2766,7 @@ retry_cpuset:
* can deadlock because I/O on the device might not
* complete.
*/
- gfp_mask = memalloc_noio_flags(gfp_mask);
+ gfp_mask = gfp_from_current(gfp_mask);
page = __alloc_pages_slowpath(gfp_mask, order,
zonelist, high_zoneidx, nodemask,
preferred_zone, migratetype);
diff --git a/mm/slab.c b/mm/slab.c
index b264214c77ea..914d88661f3d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3206,6 +3206,7 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
int slab_node = numa_mem_id();

flags &= gfp_allowed_mask;
+ flags = gfp_from_current(flags);

lockdep_trace_alloc(flags);

@@ -3293,6 +3294,7 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
void *objp;

flags &= gfp_allowed_mask;
+ flags = gfp_from_current(flags);

lockdep_trace_alloc(flags);

diff --git a/mm/slob.c b/mm/slob.c
index 4bf8809dfcce..18206f54d227 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -431,6 +431,7 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
void *ret;

gfp &= gfp_allowed_mask;
+ flags = gfp_from_current(flags);

lockdep_trace_alloc(gfp);

@@ -539,6 +540,7 @@ void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
void *b;

flags &= gfp_allowed_mask;
+ flags = gfp_from_current(flags);

lockdep_trace_alloc(flags);

diff --git a/mm/slub.c b/mm/slub.c
index 25f14ad8f817..ff7c15e977da 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -961,6 +961,7 @@ static inline void kfree_hook(const void *x)
static inline int slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags)
{
flags &= gfp_allowed_mask;
+ flags = gfp_from_current(flags);
lockdep_trace_alloc(flags);
might_sleep_if(flags & __GFP_WAIT);

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 67165f839936..05de3289d031 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2592,7 +2592,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
{
unsigned long nr_reclaimed;
struct scan_control sc = {
- .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+ .gfp_mask = (gfp_mask = gfp_from_current(gfp_mask)),
.may_writepage = !laptop_mode,
.nr_to_reclaim = SWAP_CLUSTER_MAX,
.may_unmap = 1,
@@ -3524,7 +3524,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
.may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP),
.may_swap = 1,
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
- .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+ .gfp_mask = (gfp_mask = gfp_from_current(gfp_mask)),
.order = order,
.priority = ZONE_RECLAIM_PRIORITY,
};