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fs: check FMODE_LSEEK to control internal pipe splicing
The original direct splicing mechanism from Jens required the input to
be a regular file because it was avoiding the special socket case. It
also recognized blkdevs as being close enough to a regular file. But it
forgot about chardevs, which behave the same way and work fine here.
This is an okayish heuristic, but it doesn't totally work. For example,
a few chardevs should be spliceable here. And a few regular files
shouldn't. This patch fixes this by instead checking whether FMODE_LSEEK
is set, which represents decently enough what we need rewinding for when
splicing to internal pipes.
Fixes: b92ce55893
("[PATCH] splice: add direct fd <-> fd splicing support")
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
54ef7a47f6
commit
97ef77c52b
10
fs/splice.c
10
fs/splice.c
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@ -814,17 +814,15 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
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{
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struct pipe_inode_info *pipe;
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long ret, bytes;
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umode_t i_mode;
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size_t len;
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int i, flags, more;
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/*
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* We require the input being a regular file, as we don't want to
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* randomly drop data for eg socket -> socket splicing. Use the
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* piped splicing for that!
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* We require the input to be seekable, as we don't want to randomly
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* drop data for eg socket -> socket splicing. Use the piped splicing
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* for that!
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*/
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i_mode = file_inode(in)->i_mode;
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if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
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if (unlikely(!(in->f_mode & FMODE_LSEEK)))
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return -EINVAL;
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/*
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