user/sven/linux.git/include/linux/pipe_fs_i.h, branch v3.4.15

pipes: add a "packetized pipe" mode for writing

2012-04-29T20:12:42Z

The actual internal pipe implementation is already really about individual packets (called "pipe buffers"), and this simply exposes that as a special packetized mode. When we are in the packetized mode (marked by O_DIRECT as suggested by Alan Cox), a write() on a pipe will not merge the new data with previous writes, so each write will get a pipe buffer of its own. The pipe buffer is then marked with the PIPE_BUF_FLAG_PACKET flag, which in turn will tell the reader side to break the read at that boundary (and throw away any partial packet contents that do not fit in the read buffer). End result: as long as you do writes less than PIPE_BUF in size (so that the pipe doesn't have to split them up), you can now treat the pipe as a packet interface, where each read() system call will read one packet at a time. You can just use a sufficiently big read buffer (PIPE_BUF is sufficient, since bigger than that doesn't guarantee atomicity anyway), and the return value of the read() will naturally give you the size of the packet. NOTE! We do not support zero-sized packets, and zero-sized reads and writes to a pipe continue to be no-ops. Also note that big packets will currently be split at write time, but that the size at which that happens is not really specified (except that it's bigger than PIPE_BUF). Currently that limit is the system page size, but we might want to explicitly support bigger packets some day. The main user for this is going to be the autofs packet interface, allowing us to stop having to care so deeply about exact packet sizes (which have had bugs with 32/64-bit compatibility modes). But user space can create packetized pipes with "pipe2(fd, O_DIRECT)", which will fail with an EINVAL on kernels that do not support this interface. Tested-by: Michael Tokarev Cc: Alan Cox Cc: David Miller Cc: Ian Kent Cc: Thomas Meyer Cc: stable@kernel.org # needed for systemd/autofs interaction fix Signed-off-by: Linus Torvalds

magic.h: move some FS magic numbers into magic.h

2012-03-23T23:58:31Z

- Move open-coded filesystem magic numbers into magic.h - Rearrange magic.h so that the filesystem-related constants are grouped together. Signed-off-by: Muthukumar R Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pipe_fs_i.h: fix kernel-doc warning

2011-01-10T15:38:54Z

Fix kernel-doc notation warnings in pipe_fs_i.h: Warning(include/linux/pipe_fs_i.h:58): No description found for parameter 'buffers' Signed-off-by: Randy Dunlap Signed-off-by: Linus Torvalds

Un-inline get_pipe_info() helper function

2010-11-29T00:27:19Z

This avoids some include-file hell, and the function isn't really important enough to be inlined anyway. Reported-by: Ingo Molnar Signed-off-by: Linus Torvalds

Export 'get_pipe_info()' to other users

2010-11-28T22:09:57Z

And in particular, use it in 'pipe_fcntl()'. The other pipe functions do not need to use the 'careful' version, since they are only ever called for things that are already known to be pipes. The normal read/write/ioctl functions are called through the file operations structures, so if a file isn't a pipe, they'd never get called. But pipe_fcntl() is special, and called directly from the generic fcntl code, and needs to use the same careful function that the splice code is using. Cc: Jens Axboe Cc: Andrew Morton Cc: Al Viro Cc: Dave Jones Signed-off-by: Linus Torvalds

pipe: change /proc/sys/fs/pipe-max-pages to byte sized interface

2010-06-03T12:54:39Z

This changes the interface to be based on bytes instead. The API matches that of F_SETPIPE_SZ in that it rounds up the passed in size so that the resulting page array is a power-of-2 in size. The proc file is renamed to /proc/sys/fs/pipe-max-size to reflect this change. Signed-off-by: Jens Axboe

pipe: set lower and upper limit on max pages in the pipe page array

2010-05-21T19:12:52Z

We need at least two to guarantee proper POSIX behaviour, so never allow a smaller limit than that. Also expose a /proc/sys/fs/pipe-max-pages sysctl file that allows root to define a sane upper limit. Make it default to 16 times the default size, which is 16 pages. Signed-off-by: Jens Axboe

pipe: add support for shrinking and growing pipes

2010-05-21T19:12:40Z

This patch adds F_GETPIPE_SZ and F_SETPIPE_SZ fcntl() actions for growing and shrinking the size of a pipe and adjusts pipe.c and splice.c (and relay and network splice) usage to work with these larger (or smaller) pipes. Signed-off-by: Jens Axboe

splice: implement default splice_read method

2009-05-11T12:13:10Z

If f_op->splice_read() is not implemented, fall back to a plain read. Use vfs_readv() to read into previously allocated pages. This will allow splice and functions using splice, such as the loop device, to work on all filesystems. This includes "direct_io" files in fuse which bypass the page cache. Signed-off-by: Miklos Szeredi Signed-off-by: Jens Axboe

splice: add helpers for locking pipe inode

2009-04-15T10:10:12Z

There are lots of sequences like this, especially in splice code: if (pipe->inode) mutex_lock(&pipe->inode->i_mutex); /* do something */ if (pipe->inode) mutex_unlock(&pipe->inode->i_mutex); so introduce helpers which do the conditional locking and unlocking. Also replace the inode_double_lock() call with a pipe_double_lock() helper to avoid spreading the use of this functionality beyond the pipe code. This patch is just a cleanup, and should cause no behavioral changes. Signed-off-by: Miklos Szeredi Signed-off-by: Jens Axboe