lkml.org 
[lkml]   [2009]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 2/2] Perform check in iov_iter_fault_in_readable() by check_readable_bytes()
Date
This patch changes iov_iter_fault_in_readable() to use check_readable_bytes()
instead of fault_in_pages_readable(). It allows iov_iter_fault_in_readable()
callers to know how much data is accessible and proceed with it. It makes
sys_write() more POSIX-friendly.

Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
---
fs/fuse/file.c | 6 ++++--
mm/filemap.c | 13 +++++++++----
2 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 06f30e9..c74ef04 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -782,13 +782,15 @@ static ssize_t fuse_fill_write_pages(struct fuse_req *req,
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
size_t bytes = min_t(size_t, PAGE_CACHE_SIZE - offset,
iov_iter_count(ii));
-
+ long accessible;
bytes = min_t(size_t, bytes, fc->max_write - count);

again:
err = -EFAULT;
- if (iov_iter_fault_in_readable(ii, bytes))
+ accessible = iov_iter_fault_in_readable(ii, bytes);
+ if (accessible < 0)
break;
+ bytes = accessible;

err = -ENOMEM;
page = grab_cache_page_write_begin(mapping, index, 0);
diff --git a/mm/filemap.c b/mm/filemap.c
index 379ff0b..ef598a1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1947,8 +1947,9 @@ EXPORT_SYMBOL(iov_iter_advance);

/*
* Fault in the first iovec of the given iov_iter, to a maximum length
- * of bytes. Returns 0 on success, or non-zero if the memory could not be
- * accessed (ie. because it is an invalid address).
+ * of bytes. Returns count of accessible bytes on success, or -EFAULT
+ * if the memory could not be accessed (ie. because it is an invalid
+ * address).
*
* writev-intensive code may want this to prefault several iovecs -- that
* would be possible (callers must not rely on the fact that _only_ the
@@ -1958,7 +1959,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
{
char __user *buf = i->iov->iov_base + i->iov_offset;
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
- return fault_in_pages_readable(buf, bytes);
+ return check_readable_bytes(buf, bytes);
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);

@@ -2215,6 +2216,7 @@ static ssize_t generic_perform_write(struct file *file,
unsigned long offset; /* Offset into pagecache page */
unsigned long bytes; /* Bytes to write to page */
size_t copied; /* Bytes copied from user */
+ long accessible;
void *fsdata;

offset = (pos & (PAGE_CACHE_SIZE - 1));
@@ -2234,10 +2236,13 @@ again:
* to check that the address is actually valid, when atomic
* usercopies are used, below.
*/
- if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
+
+ accessible = iov_iter_fault_in_readable(i, bytes);
+ if (accessible < 0) {
status = -EFAULT;
break;
}
+ bytes = accessible;

status = a_ops->write_begin(file, mapping, pos, bytes, flags,
&page, &fsdata);
--
1.6.2.2


\
 
 \ /
  Last update: 2009-05-14 18:23    [from the cache]
©2003-2011 Jasper Spaans