xfs: improve kmem_realloc

Use krealloc to implement our realloc function.  This helps to avoid
new allocations if we are still in the slab bucket.  At least for the
bmap btree root that's actually the common case.

This also allows removing the now unused oldsize argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 15 insertions, 11 deletions

diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
index 686ba6fb20dd..339c696bbc01 100644
--- a/fs/xfs/kmem.c
+++ b/fs/xfs/kmem.c
@@ -93,19 +93,23 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
 }
 
 void *
-kmem_realloc(const void *ptr, size_t newsize, size_t oldsize,
-             xfs_km_flags_t flags)
+kmem_realloc(const void *old, size_t newsize, xfs_km_flags_t flags)
 {
-        void    *new;
+        int     retries = 0;
+        gfp_t   lflags = kmem_flags_convert(flags);
+        void    *ptr;
 
-        new = kmem_alloc(newsize, flags);
-        if (ptr) {
-                if (new)
-                        memcpy(new, ptr,
-                                ((oldsize < newsize) ? oldsize : newsize));
-                kmem_free(ptr);
-        }
-        return new;
+        do {
+                ptr = krealloc(old, newsize, lflags);
+                if (ptr || (flags & (KM_MAYFAIL|KM_NOSLEEP)))
+                        return ptr;
+                if (!(++retries % 100))
+                        xfs_err(NULL,
+        "%s(%u) possible memory allocation deadlock size %zu in %s (mode:0x%x)",
+                                current->comm, current->pid,
+                                newsize, __func__, lflags);
+                congestion_wait(BLK_RW_ASYNC, HZ/50);
+        } while (1);
 }
 
 void *