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10 commits

Author SHA1 Message Date
Al Viro
99621b44aa btrfs: reada_extent doesn't need kref for refcount
All increments and decrements are under the same spinlock - have to be,
since they need to protect the radix_tree it's found in.  Just use
int, no need to wank with kref...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-02 21:35:55 -04:00
Stefan Behrens
3d136a1131 Btrfs: set ioprio of scrub readahead to idle
Reduce ioprio class of scrub readahead threads to idle priority.
This setting is fixed. This priority has shown the best performance
during all measurements.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
2012-05-30 10:23:43 -04:00
Arne Jansen
207a232cca btrfs: don't add both copies of DUP to reada extent tree
Normally when there are 2 copies of a block, we add both to the
reada extent tree and prefetch only the one that is easier to reach.
This way we can better utilize multiple devices.
In case of DUP this makes no sense as both copies reside on the
same device.

Signed-off-by: Arne Jansen <sensille@gmx.net>
2012-04-18 19:12:44 +02:00
Arne Jansen
8c9c2bf7a3 btrfs: fix race in reada
When inserting into the radix tree returns EEXIST, get the existing
entry without giving up the spinlock in between.
There was a race for both the zones trees and the extent tree.

Signed-off-by: Arne Jansen <sensille@gmx.net>
2012-04-18 19:12:44 +02:00
Stefan Behrens
94598ba8d8 Btrfs: introduce common define for max number of mirrors
Readahead already has a define for the max number of mirrors. Scrub
needs such a define now, the rest of the code will need something
like this soon. Therefore the define was added to ctree.h and removed
from the readahead code.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-27 14:21:26 -04:00
Chris Mason
a175423c83 Btrfs: fix casting error in scrub reada code
The reada code from scrub was casting down a u64 to
an unsigned long so it could insert it into a radix tree.

What it really wanted to do was cast down the result of a shift, instead
of casting down the u64.  The bug resulted in trying to insert our
reada struct into the wrong place, which caused soft lockups and other
problems.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-03-03 07:42:35 -05:00
Ilya Dryomov
21ca543efc Btrfs: rename btrfs_bio multi -> bbio for consistency
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:11:21 -05:00
Ilya Dryomov
9510dc4c62 Btrfs: stop leaking btrfs_bios on readahead
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:11:08 -05:00
Chris Mason
806468f8bf Merge git://git.jan-o-sch.net/btrfs-unstable into integration
Conflicts:
	fs/btrfs/Makefile
	fs/btrfs/extent_io.c
	fs/btrfs/extent_io.h
	fs/btrfs/scrub.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-06 03:07:10 -05:00
Arne Jansen
7414a03fbf btrfs: initial readahead code and prototypes
This is the implementation for the generic read ahead framework.

To trigger a readahead, btrfs_reada_add must be called. It will start
a read ahead for the given range [start, end) on tree root. The returned
handle can either be used to wait on the readahead to finish
(btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).

The read ahead works as follows:
On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
reada_start_machine will then search for extents to prefetch and trigger
some reads. When a read finishes for a node, all contained node/leaf
pointers that lie in the given range will also be enqueued. The reads will
be triggered in sequential order, thus giving a big win over a naive
enumeration. It will also make use of multi-device layouts. Each disk
will have its on read pointer and all disks will by utilized in parallel.
Also will no two disks read both sides of a mirror simultaneously, as this
would waste seeking capacity. Instead both disks will read different parts
of the filesystem.
Any number of readaheads can be started in parallel. The read order will be
determined globally, i.e. 2 parallel readaheads will normally finish faster
than the 2 started one after another.

Changes v2:
 - protect root->node by transaction instead of node_lock
 - fix missed branches:
    The readahead had a too simple check to determine if a branch from
    a node should be checked or not. It now also records the upper bound
    of each node to see if the requested RA range lies within.
 - use KERN_CONT to debug output, to avoid line breaks
 - defer reada_start_machine to worker to avoid deadlock

Changes v3:
 - protect root->node by rcu

Changes v5:
 - changed EIO-semantics of reada_tree_block_flagged
 - remove spin_lock from reada_control and make elems an atomic_t
 - remove unused read_total from reada_control
 - kill reada_key_cmp, use btrfs_comp_cpu_keys instead
 - use kref-style release functions where possible
 - return struct reada_control * instead of void * from btrfs_reada_add

Signed-off-by: Arne Jansen <sensille@gmx.net>
2011-10-02 08:48:44 +02:00