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author | Jens Axboe <jens.axboe@oracle.com> | 2007-07-13 16:11:43 +0400 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2007-07-13 16:14:31 +0400 |
commit | 51a92c0f6ce8fa85fa0e18ecda1d847e606e8066 (patch) | |
tree | b944b46d3856948931160c8a75ee27be3417c515 /fs/splice.c | |
parent | 29ce20586be54ceba49c55ae049541398cd2c416 (diff) | |
download | linux-51a92c0f6ce8fa85fa0e18ecda1d847e606e8066.tar.xz |
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>
Diffstat (limited to 'fs/splice.c')
-rw-r--r-- | fs/splice.c | 34 |
1 files 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; } |