047fe36052
Dave Jones reported a kernel BUG at mm/slub.c:3474! triggered
by splice_shrink_spd() called from vmsplice_to_pipe()
commit 35f3d14dbb (pipe: add support for shrinking and growing pipes)
added capability to adjust pipe->buffers.
Problem is some paths don't hold pipe mutex and assume pipe->buffers
doesn't change for their duration.
Fix this by adding nr_pages_max field in struct splice_pipe_desc, and
use it in place of pipe->buffers where appropriate.
splice_shrink_spd() loses its struct pipe_inode_info argument.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Tom Herbert <therbert@google.com>
Cc: stable <stable@vger.kernel.org> # 2.6.35
Tested-by: Dave Jones <davej@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
95 lines
3 KiB
C
95 lines
3 KiB
C
/*
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* Function declerations and data structures related to the splice
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* implementation.
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*
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* Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
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*
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*/
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#ifndef SPLICE_H
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#define SPLICE_H
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#include <linux/pipe_fs_i.h>
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/*
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* Flags passed in from splice/tee/vmsplice
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*/
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#define SPLICE_F_MOVE (0x01) /* move pages instead of copying */
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#define SPLICE_F_NONBLOCK (0x02) /* don't block on the pipe splicing (but */
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/* we may still block on the fd we splice */
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/* from/to, of course */
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#define SPLICE_F_MORE (0x04) /* expect more data */
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#define SPLICE_F_GIFT (0x08) /* pages passed in are a gift */
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/*
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* Passed to the actors
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*/
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struct splice_desc {
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unsigned int len, total_len; /* current and remaining length */
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unsigned int flags; /* splice flags */
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/*
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* actor() private data
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*/
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union {
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void __user *userptr; /* memory to write to */
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struct file *file; /* file to read/write */
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void *data; /* cookie */
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} u;
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loff_t pos; /* file position */
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size_t num_spliced; /* number of bytes already spliced */
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bool need_wakeup; /* need to wake up writer */
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};
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struct partial_page {
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unsigned int offset;
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unsigned int len;
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unsigned long private;
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};
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/*
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* Passed to splice_to_pipe
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*/
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struct splice_pipe_desc {
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struct page **pages; /* page map */
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struct partial_page *partial; /* pages[] may not be contig */
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int nr_pages; /* number of populated pages in map */
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unsigned int nr_pages_max; /* pages[] & partial[] arrays size */
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unsigned int flags; /* splice flags */
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const struct pipe_buf_operations *ops;/* ops associated with output pipe */
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void (*spd_release)(struct splice_pipe_desc *, unsigned int);
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};
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typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
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struct splice_desc *);
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typedef int (splice_direct_actor)(struct pipe_inode_info *,
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struct splice_desc *);
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extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,
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loff_t *, size_t, unsigned int,
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splice_actor *);
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extern ssize_t __splice_from_pipe(struct pipe_inode_info *,
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struct splice_desc *, splice_actor *);
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extern int splice_from_pipe_feed(struct pipe_inode_info *, struct splice_desc *,
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splice_actor *);
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extern int splice_from_pipe_next(struct pipe_inode_info *,
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struct splice_desc *);
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extern void splice_from_pipe_begin(struct splice_desc *);
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extern void splice_from_pipe_end(struct pipe_inode_info *,
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struct splice_desc *);
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extern int pipe_to_file(struct pipe_inode_info *, struct pipe_buffer *,
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struct splice_desc *);
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extern ssize_t splice_to_pipe(struct pipe_inode_info *,
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struct splice_pipe_desc *);
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extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
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splice_direct_actor *);
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/*
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* for dynamic pipe sizing
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*/
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extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
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extern void splice_shrink_spd(struct splice_pipe_desc *);
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extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
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extern const struct pipe_buf_operations page_cache_pipe_buf_ops;
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#endif
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