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Revision 35991652baa12ff3d0e420c0d0cb2ad9f7076e5b authored by Mikulas Patocka on 02 June 2012, 23:29:58 UTC, committed by Alasdair G Kergon on 02 June 2012, 23:29:58 UTC 
dm mpath: allow ioctls to trigger pg init
 
After the failure of a group of paths, any alternative paths that
need initialising do not become available until further I/O is sent to
the device.  Until this has happened, ioctls return -EAGAIN.

With this patch, new paths are made available in response to an ioctl
too.  The processing of the ioctl gets delayed until this has happened.

Instead of returning an error, we submit a work item to kmultipathd
(that will potentially activate the new path) and retry in ten
milliseconds.

Note that the patch doesn't retry an ioctl if the ioctl itself fails due
to a path failure.  Such retries should be handled intelligently by the
code that generated the ioctl in the first place, noting that some SCSI
commands should not be retried because they are not idempotent (XOR write
commands).  For commands that could be retried, there is a danger that
if the device rejected the SCSI command, the path could be errorneously
marked as failed, and the request would be retried on another path which
might fail too.  It can be determined if the failure happens on the
device or on the SCSI controller, but there is no guarantee that all
SCSI drivers set these flags correctly.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Raw File
jffs2_fs_i.h 
/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#ifndef _JFFS2_FS_I
#define _JFFS2_FS_I

#include <linux/rbtree.h>
#include <linux/posix_acl.h>
#include <linux/mutex.h>

struct jffs2_inode_info {
	/* We need an internal mutex similar to inode->i_mutex.
	   Unfortunately, we can't used the existing one, because
	   either the GC would deadlock, or we'd have to release it
	   before letting GC proceed. Or we'd have to put ugliness
	   into the GC code so it didn't attempt to obtain the i_mutex
	   for the inode(s) which are already locked */
	struct mutex sem;

	/* The highest (datanode) version number used for this ino */
	uint32_t highest_version;

	/* List of data fragments which make up the file */
	struct rb_root fragtree;

	/* There may be one datanode which isn't referenced by any of the
	   above fragments, if it contains a metadata update but no actual
	   data - or if this is a directory inode */
	/* This also holds the _only_ dnode for symlinks/device nodes,
	   etc. */
	struct jffs2_full_dnode *metadata;

	/* Directory entries */
	struct jffs2_full_dirent *dents;

	/* The target path if this is the inode of a symlink */
	unsigned char *target;

	/* Some stuff we just have to keep in-core at all times, for each inode. */
	struct jffs2_inode_cache *inocache;

	uint16_t flags;
	uint8_t usercompr;
	struct inode vfs_inode;
};

#endif /* _JFFS2_FS_I */
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