On Wed, 09 Apr 2008 17:57:56 +0200
We found suspicious-looking code in generic_file_splice_read() back in
February. See http://lkml.org/lkml/2008/2/29/443. I suspect that patch
(if it works) will address the truncate lockup as well - it zaps the loop
entirely.
Unfortunately Allard never got back to us (probably because he's running
2.6.24 which has a quite different generic_file_splice_read()) and the
patch didn't get anywhere.
Here it is again.
It needs a changelog.
Nobody has tested this at all, to my knowledge.
It's going to take some serious and sudden effort to get these bugs fixed
for 2.6.25.
fs/splice.c | 31 ++++++-------------------------
1 file changed, 6 insertions(+), 25 deletions(-)
diff -puN fs/splice.c~generic_file_splice_read-fix-lockups fs/splice.c
--- a/fs/splice.c~generic_file_splice_read-fix-lockups
+++ a/fs/splice.c
@@ -370,8 +370,10 @@ __generic_file_splice_read(struct file *
* for an in-flight io page
*/
if (flags & SPLICE_F_NONBLOCK) {
- if (TestSetPageLocked(page))
+ if (TestSetPageLocked(page)) {
+ error = -EAGAIN;
break;
+ }
} else
lock_page(page);
@@ -479,9 +481,8 @@ ssize_t generic_file_splice_read(struct
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
- ssize_t spliced;
- int ret;
loff_t isize, left;
+ int ret;
isize = i_size_read(in->f_mapping->host);
if (unlikely(*ppos >= isize))
@@ -491,29 +492,9 @@ ssize_t generic_file_splice_read(struct
if (unlikely(left < len))
len = left;
- ret = 0;
- spliced = 0;
- while (len && !spliced) {
- ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
-
- if (ret < 0)
- break;
- else if (!ret) {
- if (spliced)
- break;
- if (flags & SPLICE_F_NONBLOCK) {
- ret = -EAGAIN;
- break;
- }
- }
-
+ ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
+ if (ret > 0)
*ppos += ret;
- len -= ret;
- spliced += ret;
- }
-
- if ...
