pstore only allows one backend to be registered at present, but the
system may provide several. Add a parameter to allow the user to choose
which backend will be used rather than just relying on load order.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

We'll never have a negative part, so just make this an unsigned int.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

EFI only provides small amounts of individual storage, and conventionally
puts metadata in the storage variable name. Rather than add a metadata
header to the (already limited) variable storage, it's easier for us to
modify pstore to pass all the information we need to construct a unique
variable name to the appropriate functions.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Some pstore implementations may not have a static context, so extend the
API to pass the pstore_info struct to all calls and allow for a context
pointer.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Currently after mount/remount operation on pstore filesystem,
the content on pstore will be lost. It is because current ERST
implementation doesn't support multi-user usage, which moves
internal pointer to the end after accessing it. Adding
multi-user support for pstore usage.
Signed-off-by: NChen Gong <gong.chen@linux.intel.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

the return type of function _read_ in pstore is size_t,
but in the callback function of _read_, the logic doesn't
consider it too much, which means if negative value (assuming
error here) is returned, it will be converted to positive because
of type casting. ssize_t is enough for this function.
Signed-off-by: NChen Gong <gong.chen@linux.intel.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

pstore_dump() can be called with many different "reason" codes. Save
the name of the code in the persistent store record.

Also - only worthwhile calling pstore_mkfile for KMSG_DUMP_OOPS - that
is the only one where the kernel will continue running.
Reviewed-by: NSeiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

/sys/fs is a somewhat strange way to tweak what could more
obviously be tuned with a mount option.
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some platforms have a small amount of non-volatile storage that
can be used to store information useful to diagnose the cause of
a system crash.  This is the generic part of a file system interface
that presents information from the crash as a series of files in
/dev/pstore.  Once the information has been seen, the underlying
storage is freed by deleting the files.
Signed-off-by: NTony Luck <tony.luck@intel.com>