From: Jens Axboe Date: Fri, 13 Jul 2007 12:11:43 +0000 (+0200) Subject: splice: fix offset mangling with direct splicing (sendfile) X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=51a92c0f6ce8fa85fa0e18ecda1d847e606e8066;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 --- 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; }