[PATCH v7 00/19] xfs: Delayed Ready Attrs

Allison Collins
2020-02-23T02:06:21Z

Hi all,

This set is a subset of a larger series for delayed attributes. Which is
a subset of an even larger series, parent pointers. Delayed attributes
allow attribute operations (set and remove) to be logged and committed
in the same way that other delayed operations do. This allows more
complex operations (like parent pointers) to be broken up into multiple
smaller transactions. To do this, the existing attr operations must be
modified to operate as either a delayed operation or a inline operation
since older filesystems will not be able to use the new log entries.
This means that they cannot roll, commit, or finish transactions.
Instead, they return EAGAIN an allow the calling function to handle
the transaction. In this series, we focus on only the clean up and
refactoring needed to accomplish this. We will introduce delayed attrs
and parent pointers in a later set.

At the moment, I would like people to focus their review efforts on just
this "delay ready" subseries, as I think that is a more conservative use
of peoples review time. I also think the set is a bit much to manage
all at once, and we need to get the infrastructure ironed out before we
focus too much anything that depends on it. But I do have the extended
series for folks that want to see the bigger picture of where this is
going.

This series can be viewed on github here:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v7

As well as the extended delayed attribute and parent pointer series:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v7_extended

And the test cases:
https://github.com/allisonhenderson/xfs_work/tree/pptr_xfstests

To run the xfs attributes tests run:
check -g attr

To run as delayed attributes run:
export MKFS_OPTIONS="-n delattr"
check -g attr

To run parent pointer tests:
check -g parent

Changes since v6:
Mostly review just updates. In the last review folks asked for a
diagram to make the code flow more visual. They have been added in
patches 13 and 14. At the moment, they're in the commit message. I
figure people can decide where or if they want them somewhere in the
code later, since they are a bit lengthy. Patch 15 is a helper function
that used to be part of 14 but I separated it to better organize things.
Patches 18 and 19 are new, and are just cleanups that I thought would
be helpful.

I've also gone through the set and rearranged the order of some of the
patches to make sort of mini sets. I thought it would help reviewers
break down the reviewing some. For reviewing purposes, the set could be
broken up into 5 different phases:

Clean ups (patches 1-2):
These two patches were actually review suggestions made quiet some time
ago in regaurds to commit d29f781 (Remove all strlen ...), which has
since been merged. The idea of the cleanups was to collapse down the
number of parameters getting passed around the xfs_attr_* routines. It
has since drawn both commentary and critisim, so it's a little unclear
to me if people want it or not. It could easily be taken as a stand
alone clean up. But it's also not a neccassary must have in so far as
the delayed operations are concerned. It does however pepper around a
lot of change activity up through the set. So it would be helpfull to
get a verdict one way or another, depending on how people feel about it.
xfs: Replace attribute parameters with struct xfs_name
xfs: Embed struct xfs_name in xfs_da_args

Error code filtering (patches 3-4):
These two patches are all about finding and catching error codes that
need to be sent back up to user space before starting delayed
operations. Errors that happen during a delayed operation are treated
like interal errors that cause a shutdown. But we wouldnt want that
for example: when the user tries to rename a non existent attr. So the
idea is that we need to find all such conditions, and take care of them
before starting a delayed operation.
xfs: Add xfs_has_attr and subroutines
xfs: Check for -ENOATTR or -EEXIST

Move transactions upwards (patches 5-12):
The goal of this subset is to try and move all the transaction specific
code up the call stack much as possible. The idea being that once we
get them to the top, we can introduce the statemachine to handle the
-EAGAIN logic where ever the transactions used to be.
xfs: Factor out new helper functions xfs_attr_rmtval_set
xfs: Factor out trans handling in xfs_attr3_leaf_flipflags
xfs: Factor out xfs_attr_leaf_addname helper
xfs: Refactor xfs_attr_try_sf_addname
xfs: Factor out trans roll from xfs_attr3_leaf_setflag
xfs: Factor out xfs_attr_rmtval_invalidate
xfs: Factor out trans roll in xfs_attr3_leaf_clearflag
xfs: Add helper function xfs_attr_rmtval_unmap

Introduce statemachine (patches 13-14):
Now that we have re-arranged the code such that we can remove the
transaction handleing, we proceed to do so. The behavior of the attr
set/remove routines are now also compatible as a .finish_item callback
xfs: Add delay ready attr remove routines
xfs: Add delay ready attr set routines

Modularizing and cleanups (patches 15-19):
Now that we have pulled the transactions up to where we need them, it's
time to start breaking down the top level functions into new
subfunctions. The goal being to work towards a top level function that
deals mostly with the statemachine, and helpers for those states
xfs: Add helper function xfs_attr_node_shrink
xfs: Simplify xfs_attr_set_iter
xfs: Add helper function xfs_attr_leaf_mark_incomplete
xfs: Add remote block helper functions
xfs: Remove xfs_attr_rmtval_remove

I've also made the corresponding updates to the user space side as well.

Questions, comment and feedback appreciated!

Thanks all!
Allison

Allison Collins (18):
xfs: Replace attribute parameters with struct xfs_name
xfs: Embed struct xfs_name in xfs_da_args
xfs: Check for -ENOATTR or -EEXIST
xfs: Factor out new helper functions xfs_attr_rmtval_set
xfs: Factor out trans handling in xfs_attr3_leaf_flipflags
xfs: Factor out xfs_attr_leaf_addname helper
xfs: Refactor xfs_attr_try_sf_addname
xfs: Factor out trans roll from xfs_attr3_leaf_setflag
xfs: Factor out xfs_attr_rmtval_invalidate
xfs: Factor out trans roll in xfs_attr3_leaf_clearflag
xfs: Add helper function xfs_attr_rmtval_unmap
xfs: Add delay ready attr remove routines
xfs: Add delay ready attr set routines
xfs: Add helper function xfs_attr_node_shrink
xfs: Simplify xfs_attr_set_iter
xfs: Add helper function xfs_attr_leaf_mark_incomplete
xfs: Add remote block helper functions
xfs: Remove xfs_attr_rmtval_remove

Allison Henderson (1):
xfs: Add xfs_has_attr and subroutines

fs/xfs/libxfs/xfs_attr.c | 947 ++++++++++++++++++++++++++++------------
fs/xfs/libxfs/xfs_attr.h | 15 +-
fs/xfs/libxfs/xfs_attr_leaf.c | 220 +++++-----
fs/xfs/libxfs/xfs_attr_leaf.h | 3 +
fs/xfs/libxfs/xfs_attr_remote.c | 260 +++++++----
fs/xfs/libxfs/xfs_attr_remote.h | 7 +-
fs/xfs/libxfs/xfs_da_btree.c | 6 +-
fs/xfs/libxfs/xfs_da_btree.h | 47 +-
fs/xfs/libxfs/xfs_dir2.c | 18 +-
fs/xfs/libxfs/xfs_dir2_block.c | 6 +-
fs/xfs/libxfs/xfs_dir2_leaf.c | 6 +-
fs/xfs/libxfs/xfs_dir2_node.c | 8 +-
fs/xfs/libxfs/xfs_dir2_sf.c | 30 +-
fs/xfs/libxfs/xfs_types.c | 11 +
fs/xfs/libxfs/xfs_types.h | 1 +
fs/xfs/scrub/attr.c | 12 +-
fs/xfs/scrub/common.c | 2 +
fs/xfs/xfs_acl.c | 27 +-
fs/xfs/xfs_attr_list.c | 1 +
fs/xfs/xfs_ioctl.c | 25 +-
fs/xfs/xfs_ioctl32.c | 2 +
fs/xfs/xfs_iops.c | 8 +-
fs/xfs/xfs_trace.h | 21 +-
fs/xfs/xfs_xattr.c | 29 +-
24 files changed, 1140 insertions(+), 572 deletions(-)

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2.7.4