From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Jones <davej@codemonkey.org.uk>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: iov_iter_pipe warning.
Date: Wed, 12 Apr 2017 16:26:00 +0100 [thread overview]
Message-ID: <20170412152600.GP29622@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170412143519.4hh36l3egozgdrll@codemonkey.org.uk>
On Wed, Apr 12, 2017 at 10:35:19AM -0400, Dave Jones wrote:
> [ 4140.040002] asked to read 8, claims to have read 4
> [ 4140.051634] actual size of data in pipe 8
> [ 4140.063234] [0:8
> [ 4140.342955] ---[ end trace d074a8823fe244d4 ]---
> [ 4140.353868] in->f_op = ffffffffa02dc980, ->splice_write = ffffffff812b2c20
IOW, we just had someone's ->read_iter() return 4 after having deposited 8
bytes. The next question is which file_operations had that been, whether
it was O_DIRECT or not and where in file had we been reading from...
diff --git a/fs/splice.c b/fs/splice.c
index 006ba50f4ece..0e67ddf8618d 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -284,6 +284,43 @@ void splice_shrink_spd(struct splice_pipe_desc *spd)
kfree(spd->partial);
}
+static bool test_it(struct pipe_inode_info *pipe, size_t len, long ret)
+{
+ int idx = pipe->curbuf;
+ int n = pipe->nrbufs;
+ size_t size = 0;
+ while (n--) {
+ size += pipe->bufs[idx++].len;
+ if (idx == pipe->buffers)
+ idx = 0;
+ }
+ if (WARN_ON(size != ret)) {
+ char c = '[';
+ printk(KERN_ERR "asked to read %zu, claims to have read %ld",
+ len, ret);
+ printk(KERN_CONT "actual size of data in pipe %zd ", size);
+ for (n = pipe->nrbufs, idx = pipe->curbuf; n--; ) {
+ printk(KERN_CONT "%c%d:%u", c, idx,
+ pipe->bufs[idx].len);
+ c = ',';
+ if (++idx == pipe->buffers)
+ idx = 0;
+ }
+ if (c != '[')
+ printk(KERN_CONT "]");
+ return true;
+ }
+ return false;
+}
+
+static inline bool insane_splice_read(struct pipe_inode_info *pipe,
+ size_t len, long ret)
+{
+ if (ret <= 0 || pipe != current->splice_pipe)
+ return false;
+ return test_it(pipe, len, ret);
+}
+
/**
* generic_file_splice_read - splice data from file to a pipe
* @in: file to splice from
@@ -311,8 +348,14 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
kiocb.ki_pos = *ppos;
ret = call_read_iter(in, &kiocb, &to);
if (ret > 0) {
- *ppos = kiocb.ki_pos;
file_accessed(in);
+ if (unlikely(insane_splice_read(pipe, len, ret))) {
+ printk(KERN_ERR "f_op: %p, f_flags: %d, pos: %lld/%lld, size: %lld",
+ in->f_op, in->f_flags, (long long)*ppos,
+ (long long)kiocb.ki_pos,
+ (long long)i_size_read(file_inode(in)));
+ }
+ *ppos = kiocb.ki_pos;
} else if (ret < 0) {
to.idx = idx;
to.iov_offset = 0;
@@ -394,7 +437,7 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
struct page **pages;
unsigned int nr_pages;
size_t offset, dummy, copied = 0;
- ssize_t res;
+ ssize_t res, old_len = len;
int i;
if (pipe->nrbufs == pipe->buffers)
@@ -448,6 +491,7 @@ static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
put_page(pages[i]);
kvfree(pages);
iov_iter_advance(&to, copied); /* truncates and discards */
+ insane_splice_read(pipe, old_len, res);
return res;
}
@@ -970,6 +1014,11 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
while (len) {
size_t read_len;
loff_t pos = sd->pos, prev_pos = pos;
+ if (WARN_ON(pipe->nrbufs)) {
+ printk(KERN_ERR "in->f_op = %p, ->splice_write = %p\n",
+ in->f_op,
+ sd->u.file->f_op->splice_write);
+ }
ret = do_splice_to(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
next prev parent reply other threads:[~2017-04-12 15:26 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-21 20:59 iov_iter_pipe warning Dave Jones
2017-04-05 22:02 ` Dave Jones
2017-04-10 19:28 ` Al Viro
2017-04-10 19:42 ` Dave Jones
2017-04-10 19:57 ` Al Viro
2017-04-10 23:48 ` Dave Jones
2017-04-11 0:22 ` Al Viro
2017-04-11 3:05 ` Dave Jones
2017-04-11 3:28 ` Al Viro
2017-04-11 20:53 ` Dave Jones
2017-04-11 21:12 ` Al Viro
2017-04-11 22:25 ` Dave Jones
2017-04-11 23:28 ` Al Viro
2017-04-11 23:34 ` Dave Jones
2017-04-11 23:48 ` Al Viro
2017-04-11 23:45 ` Dave Jones
2017-04-11 23:51 ` Al Viro
2017-04-11 23:56 ` Al Viro
2017-04-12 0:06 ` Dave Jones
2017-04-12 0:17 ` Al Viro
2017-04-12 0:58 ` Dave Jones
2017-04-12 1:15 ` Al Viro
2017-04-12 2:29 ` Dave Jones
2017-04-12 2:58 ` Al Viro
2017-04-12 14:35 ` Dave Jones
2017-04-12 15:26 ` Al Viro [this message]
2017-04-12 16:27 ` Dave Jones
2017-04-12 17:07 ` Al Viro
2017-04-12 19:03 ` Dave Jones
2017-04-21 17:54 ` Al Viro
2017-04-27 4:19 ` Dave Jones
2017-04-27 16:34 ` Dave Jones
2017-04-27 17:39 ` Al Viro
2017-04-28 15:29 ` Dave Jones
2017-04-28 16:43 ` Al Viro
2017-04-28 16:50 ` Dave Jones
2017-04-28 17:20 ` Al Viro
2017-04-28 18:25 ` Al Viro
2017-04-29 1:58 ` Dave Jones
2017-04-29 2:47 ` Al Viro
2017-04-29 15:51 ` Dave Jones
2017-04-29 20:46 ` [git pull] vfs.git fix (Re: iov_iter_pipe warning.) Al Viro
2017-08-07 20:18 ` iov_iter_pipe warning Dave Jones
2017-08-28 20:31 ` Dave Jones
2017-08-29 4:25 ` Darrick J. Wong
2017-08-30 17:05 ` Dave Jones
2017-08-30 17:13 ` Darrick J. Wong
2017-08-30 17:17 ` Dave Jones
2017-09-06 20:03 ` Dave Jones
2017-09-06 23:46 ` Dave Chinner
2017-09-07 3:48 ` Dave Jones
2017-09-07 4:33 ` Al Viro
2017-09-08 1:04 ` Al Viro
2017-09-10 1:07 ` Dave Jones
2017-09-10 2:57 ` Al Viro
2017-09-10 16:07 ` Dave Jones
2017-09-10 20:05 ` Al Viro
2017-09-10 20:07 ` Dave Jones
2017-09-10 20:33 ` Al Viro
2017-09-10 21:11 ` Dave Chinner
2017-09-10 21:19 ` Al Viro
2017-09-10 22:08 ` Dave Chinner
2017-09-10 23:07 ` Al Viro
2017-09-10 23:15 ` Al Viro
2017-09-11 0:31 ` Dave Chinner
2017-09-11 3:32 ` Al Viro
2017-09-11 6:44 ` Dave Chinner
2017-09-11 20:07 ` Al Viro
2017-09-11 20:17 ` Al Viro
2017-09-12 6:02 ` Dave Chinner
2017-09-12 11:13 ` Al Viro
2017-09-11 12:07 ` Christoph Hellwig
2017-09-11 12:51 ` Al Viro
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