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authorNick Piggin <npiggin@suse.de>2007-10-16 01:24:58 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 09:42:54 -0700
commit4a9e5ef1f4f15205e477817a5cefc34bd3f65f55 (patch)
tree51f52086ecbccc3f41955d8d12293ef7a566a05b /mm/filemap.h
parenteb2be189317d031895b5ca534fbf735eb546158b (diff)
downloadop-kernel-dev-4a9e5ef1f4f15205e477817a5cefc34bd3f65f55.zip
op-kernel-dev-4a9e5ef1f4f15205e477817a5cefc34bd3f65f55.tar.gz
mm: write iovec cleanup
Hide some of the open-coded nr_segs tests into the iovec helpers. This is all to simplify generic_file_buffered_write, because that gets more complex in the next patch. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/filemap.h')
-rw-r--r--mm/filemap.h100
1 files changed, 50 insertions, 50 deletions
diff --git a/mm/filemap.h b/mm/filemap.h
index a1e10a2..b500d93 100644
--- a/mm/filemap.h
+++ b/mm/filemap.h
@@ -22,82 +22,82 @@ __filemap_copy_from_user_iovec_inatomic(char *vaddr,
/*
* 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).
+ * were sucessfully copied. If a fault is encountered then return the number of
+ * bytes which were copied.
*/
static inline size_t
-filemap_copy_from_user(struct page *page, unsigned long offset,
- const char __user *buf, unsigned bytes)
+filemap_copy_from_user_atomic(struct page *page, unsigned long offset,
+ const struct iovec *iov, unsigned long nr_segs,
+ size_t base, size_t bytes)
{
char *kaddr;
- int left;
+ size_t copied;
kaddr = kmap_atomic(page, KM_USER0);
- left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes);
+ if (likely(nr_segs == 1)) {
+ int left;
+ char __user *buf = iov->iov_base + base;
+ left = __copy_from_user_inatomic_nocache(kaddr + offset,
+ buf, bytes);
+ copied = bytes - left;
+ } else {
+ copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset,
+ iov, base, bytes);
+ }
kunmap_atomic(kaddr, KM_USER0);
- if (left != 0) {
- /* Do it the slow way */
- kaddr = kmap(page);
- left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
- kunmap(page);
- }
- return bytes - left;
+ return copied;
}
/*
- * This has the same sideeffects and return value as filemap_copy_from_user().
- * The difference is that on a fault we need to memset the remainder of the
- * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
- * single-segment behaviour.
+ * This has the same sideeffects and return value as
+ * filemap_copy_from_user_atomic().
+ * The difference is that it attempts to resolve faults.
*/
static inline size_t
-filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
- const struct iovec *iov, size_t base, size_t bytes)
+filemap_copy_from_user(struct page *page, unsigned long offset,
+ const struct iovec *iov, unsigned long nr_segs,
+ size_t base, size_t bytes)
{
char *kaddr;
size_t copied;
- kaddr = kmap_atomic(page, KM_USER0);
- 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_inatomic(kaddr + offset, iov,
- base, bytes);
- if (bytes - copied)
- memset(kaddr + offset + copied, 0, bytes - copied);
- kunmap(page);
+ kaddr = kmap(page);
+ if (likely(nr_segs == 1)) {
+ int left;
+ char __user *buf = iov->iov_base + base;
+ left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
+ copied = bytes - left;
+ } else {
+ copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset,
+ iov, base, bytes);
}
+ kunmap(page);
return copied;
}
static inline void
-filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
+filemap_set_next_iovec(const struct iovec **iovp, unsigned long nr_segs,
+ size_t *basep, size_t bytes)
{
- const struct iovec *iov = *iovp;
- size_t base = *basep;
+ if (likely(nr_segs == 1)) {
+ *basep += bytes;
+ } else {
+ const struct iovec *iov = *iovp;
+ size_t base = *basep;
- while (bytes) {
- int copy = min(bytes, iov->iov_len - base);
+ while (bytes) {
+ int copy = min(bytes, iov->iov_len - base);
- bytes -= copy;
- base += copy;
- if (iov->iov_len == base) {
- iov++;
- base = 0;
+ bytes -= copy;
+ base += copy;
+ if (iov->iov_len == base) {
+ iov++;
+ base = 0;
+ }
}
+ *iovp = iov;
+ *basep = base;
}
- *iovp = iov;
- *basep = base;
}
#endif
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