From 51a92c0f6ce8fa85fa0e18ecda1d847e606e8066 Mon Sep 17 00:00:00 2001
From: Jens Axboe <jens.axboe@oracle.com>
Date: Fri, 13 Jul 2007 14:11:43 +0200
Subject: [PATCH] splice: fix offset mangling with direct splicing (sendfile)
If the output actor doesn't transfer the full amount of data, we will
increment ppos too much. Two related bugs in there:
- We need to break out and return actor() retval if it is shorted than
what we spliced into the pipe.
- Adjust ppos only according to actor() return.
Also fix loop problem in generic_file_splice_read(), it should not keep
going when data has already been transferred.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/splice.c | 34 +++++++++++-----------------------
1 file changed, 11 insertions(+), 23 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index ef808227bc11..6c9828651e6f 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -492,7 +492,7 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
ret = 0;
spliced = 0;
- while (len) {
+ while (len && !spliced) {
ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
if (ret < 0)
@@ -1060,15 +1060,10 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
sd->flags &= ~SPLICE_F_NONBLOCK;
while (len) {
- size_t read_len, max_read_len;
-
- /*
- * Do at most PIPE_BUFFERS pages worth of transfer:
- */
- max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
+ size_t read_len;
- ret = do_splice_to(in, &sd->pos, pipe, max_read_len, flags);
- if (unlikely(ret < 0))
+ ret = do_splice_to(in, &sd->pos, pipe, len, flags);
+ if (unlikely(ret <= 0))
goto out_release;
read_len = ret;
@@ -1080,26 +1075,17 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
* could get stuck data in the internal pipe:
*/
ret = actor(pipe, sd);
- if (unlikely(ret < 0))
+ if (unlikely(ret <= 0))
goto out_release;
bytes += ret;
len -= ret;
- /*
- * In nonblocking mode, if we got back a short read then
- * that was due to either an IO error or due to the
- * pagecache entry not being there. In the IO error case
- * the _next_ splice attempt will produce a clean IO error
- * return value (not a short read), so in both cases it's
- * correct to break out of the loop here:
- */
- if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
- break;
+ if (ret < read_len)
+ goto out_release;
}
pipe->nrbufs = pipe->curbuf = 0;
-
return bytes;
out_release:
@@ -1161,10 +1147,12 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
.pos = *ppos,
.u.file = out,
};
- size_t ret;
+ long ret;
ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
- *ppos = sd.pos;
+ if (ret > 0)
+ *ppos += ret;
+
return ret;
}
--
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