path: root/fs/relayfs/relay.h (follow)
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2006-01-08[PATCH] relayfs: export relayfs_create_file() with fileops paramTom Zanussi1-4/+0
This patch adds a mandatory fileops param to relayfs_create_file() and exports that function so that clients can use it to create files defined by their own set of file operations, in relayfs. The purpose is to allow relayfs applications to create their own set of 'control' files alongside their relay files in relayfs rather than having to create them in /proc or debugfs for instance. relayfs_create_file() is also used by relay_open_buf() to create the relay files for a channel. In this case, a pointer to relayfs_file_operations is passed in, along with a pointer to the buffer associated with the file. Signed-off-by: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] relayfs: decouple buffer creation from inode creationTom Zanussi1-1/+1
The patch series implementa or fixes 3 things that were specifically requested or suggested by relayfs users: - support for non-relay files (patches 1-6) Currently, the relayfs API only supports the creation of directories (relayfs_create_dir()) and relay files (relay_open()). These patches adds support for non-relay files (relayfs_create_file()). This is so relayfs applications can create 'control files' in relayfs itself rather than in /proc or via a netlink channel, as is currently done in the relay-app examples. Basically what this amounts to is exporting relayfs_create_file() with an additional file_ops param that clients can use to supply file operations for their own special-purpose files in relayfs. - make exported relay file ops useful (patches 7-8) The relayfs relay_file_operations have always been exported, the intent being to make it possible to create relay files in other filesystems such as debugfs. The problem, though, is that currently the file operations are too tightly coupled to relayfs to actually be used for this purpose. This patch fixes that by adding a couple of callback functions that allow a client to hook into relay_open()/close() and supply the files that will be used to represent the channel buffers; the default implementation if no callbacks are defined is to create the files in relayfs. - add an option to create global relay buffer (patches 9-10) The file creation callback also supplies an optional param, is_global, that can be used by clients to create a single global relayfs buffer instead of the default per-cpu buffers. This was suggested as being useful for certain debugging applications where it's more convenient to be able to get all the data from a single channel without having to go to the bother of dealing with per-cpu files. - cleanup, some renaming and Documentation updates (patches 11-12) There were several comments that the use of netlink in the example code was non-intuitive and in fact the whole relay-app business was needlessly confusing. Based on that feedback, the example code has been completely converted over to relayfs control files as supported by this patch, and have also been made completely self-contained. The converted examples along with a couple of new examples that demonstrate using exported relay files can be found in relay-apps tarball: http://prdownloads.sourceforge.net/relayfs/relay-apps-0.9.tar.gz?download This patch: Separate buffer create/destroy from inode create/destroy. We want to be able to associate other data and not just relay buffers with inodes. Buffer create/destroy is moved out of inode.c and into relayfs core code. Signed-off-by: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] relayfsTom Zanussi1-0/+12
Here's the latest version of relayfs, against linux-2.6.11-mm2. I'm hoping you'll consider putting this version back into your tree - the previous rounds of comment seem to have shaken out all the API issues and the number of comments on the code itself have also steadily dwindled. This patch is essentially the same as the relayfs redux part 5 patch, with some minor changes based on reviewer comments. Thanks again to Pekka Enberg for those. The patch size without documentation is now a little smaller at just over 40k. Here's a detailed list of the changes: - removed the attribute_flags in relay open and changed it to a boolean specifying either overwrite or no-overwrite mode, and removed everything referencing the attribute flags. - added a check for NULL names in relayfs_create_entry() - got rid of the unnecessary multiple labels in relay_create_buf() - some minor simplification of relay_alloc_buf() which got rid of a couple params - updated the Documentation In addition, this version (through code contained in the relay-apps tarball linked to below, not as part of the relayfs patch) tries to make it as easy as possible to create the cooperating kernel/user pieces of a typical and common type of logging application, one where kernel logging is kicked off when a user space data collection app starts and stops when the collection app exits, with the data being automatically logged to disk in between. To create this type of application, you basically just include a header file (relay-app.h, included in the relay-apps tarball) in your kernel module, define a couple of callbacks and call an initialization function, and on the user side call a single function that sets up and continuously monitors the buffers, and writes data to files as it becomes available. Channels are created when the collection app is started and destroyed when it exits, not when the kernel module is inserted, so different channel buffer sizes can be specified for each separate run via command-line options. See the README in the relay-apps tarball for details. Also included in the relay-apps tarball are a couple examples demonstrating how you can use this to create quick and dirty kernel logging/debugging applications. They are: - tprintk, short for 'tee printk', which temporarily puts a kprobe on printk() and writes a duplicate stream of printk output to a relayfs channel. This could be used anywhere there's printk() debugging code in the kernel which you'd like to exercise, but would rather not have your system logs cluttered with debugging junk. You'd probably want to kill klogd while you do this, otherwise there wouldn't be much point (since putting a kprobe on printk() doesn't change the output of printk()). I've used this method to temporarily divert the packet logging output of the iptables LOG target from the system logs to relayfs files instead, for instance. - klog, which just provides a printk-like formatted logging function on top of relayfs. Again, you can use this to keep stuff out of your system logs if used in place of printk. The example applications can be found here: http://prdownloads.sourceforge.net/dprobes/relay-apps.tar.gz?download From: Christoph Hellwig <hch@lst.de> avoid lookup_hash usage in relayfs Signed-off-by: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>