Fix NUMA Memory Policy Reference Counting

[sfrench/cifs-2.6.git] / mm / filemap.h

diff --git a/mm/filemap.h b/mm/filemap.h
index 13793ba0ce172714355abee0ddd3291622370461..c2bff04c84ed42cfd7b1c85e9819785ae90f6c87 100644 (file)
--- a/mm/filemap.h
+++ b/mm/filemap.h
@@ -12,19 +12,26 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/uio.h>
-#include <linux/config.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 
 size_t
-__filemap_copy_from_user_iovec(char *vaddr,
-                              const struct iovec *iov,
-                              size_t base,
-                              size_t bytes);
+__filemap_copy_from_user_iovec_inatomic(char *vaddr,
+                                       const struct iovec *iov,
+                                       size_t base,
+                                       size_t bytes);
 
 /*
  * Copy as much as we can into the page and return the number of bytes which
  * were sucessfully copied.  If a fault is encountered then clear the page
  * out to (offset+bytes) and return the number of bytes which were copied.
+ *
+ * NOTE: For this to work reliably we really want copy_from_user_inatomic_nocache
+ * to *NOT* zero any tail of the buffer that it failed to copy.  If it does,
+ * and if the following non-atomic copy succeeds, then there is a small window
+ * where the target page contains neither the data before the write, nor the
+ * data after the write (it contains zero).  A read at this time will see
+ * data that is inconsistent with any ordering of the read and the write.
+ * (This has been detected in practice).
  */
 static inline size_t
 filemap_copy_from_user(struct page *page, unsigned long offset,
@@ -34,13 +41,13 @@ filemap_copy_from_user(struct page *page, unsigned long offset,
        int left;
 
        kaddr = kmap_atomic(page, KM_USER0);
-       left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
+       left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes);
        kunmap_atomic(kaddr, KM_USER0);
 
        if (left != 0) {
                /* Do it the slow way */
                kaddr = kmap(page);
-               left = __copy_from_user(kaddr + offset, buf, bytes);
+               left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
                kunmap(page);
        }
        return bytes - left;
@@ -60,13 +67,15 @@ filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
        size_t copied;
 
        kaddr = kmap_atomic(page, KM_USER0);
-       copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
-                                               base, bytes);
+       copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov,
+                                                        base, bytes);
        kunmap_atomic(kaddr, KM_USER0);
        if (copied != bytes) {
                kaddr = kmap(page);
-               copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
-                                                       base, bytes);
+               copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov,
+                                                                base, bytes);
+               if (bytes - copied)
+                       memset(kaddr + offset + copied, 0, bytes - copied);
                kunmap(page);
        }
        return copied;
@@ -78,7 +87,7 @@ filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
        const struct iovec *iov = *iovp;
        size_t base = *basep;
 
-       while (bytes) {
+       do {
                int copy = min(bytes, iov->iov_len - base);
 
                bytes -= copy;
@@ -87,7 +96,7 @@ filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
                        iov++;
                        base = 0;
                }
-       }
+       } while (bytes);
        *iovp = iov;
        *basep = base;
 }