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authorAnton Altaparmakov <anton@tuxera.com>2015-03-11 17:43:31 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2015-04-12 05:24:32 +0300
commit171a02032bf1e1bb35442a38d6e25e0dcbb85c63 (patch)
treea374f6fcd3290ccce1872c6013799dc8c171a31e
parente5b811e38af7540b385c898d83eb0198310343fd (diff)
downloadlinux-171a02032bf1e1bb35442a38d6e25e0dcbb85c63.tar.xz
VFS: Add iov_iter_fault_in_multipages_readable()
simillar to iov_iter_fault_in_readable() but differs in that it is not limited to faulting in the first iovec and instead faults in "bytes" bytes iterating over the iovecs as necessary. Also, instead of only faulting in the first and last page of the range, all pages are faulted in. This function is needed by NTFS when it does multi page file writes. Signed-off-by: Anton Altaparmakov <anton@tuxera.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--include/linux/uio.h1
-rw-r--r--lib/iov_iter.c26
2 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 71880299ed48..a69ed25af07f 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -76,6 +76,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes);
void iov_iter_advance(struct iov_iter *i, size_t bytes);
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
+int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 9d96e283520c..b80f84376b91 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -317,6 +317,32 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
+/*
+ * Fault in one or more iovecs of the given iov_iter, to a maximum length of
+ * bytes. For each iovec, fault in each page that constitutes the iovec.
+ *
+ * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
+ * because it is an invalid address).
+ */
+int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes)
+{
+ size_t skip = i->iov_offset;
+ const struct iovec *iov;
+ int err;
+ struct iovec v;
+
+ if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+ iterate_iovec(i, bytes, v, iov, skip, ({
+ err = fault_in_multipages_readable(v.iov_base,
+ v.iov_len);
+ if (unlikely(err))
+ return err;
+ 0;}))
+ }
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_fault_in_multipages_readable);
+
void iov_iter_init(struct iov_iter *i, int direction,
const struct iovec *iov, unsigned long nr_segs,
size_t count)