The was a problem when self-heal was sending lookups at the same time
that one of the bricks was coming up. In this case there was a chance
that the number of 'up' bricks changes in the middle of sending the
requests to subvolumes which caused a discrepancy in the expected
number of replies and the actual number of sent requests.

This discrepancy caused that AFR continued executing requests before
all requests were complete. Eventually, the frame of the pending
request was destroyed when the operation terminated, causing a use-
after-free issue when the answer was finally received.

In theory the same thing could happen in the reverse way, i.e. AFR
tries to wait for more replies than sent requests, causing a hang.

Backport of:
> Change-Id: I7ed6108554ca379d532efb1a29b2de8085410b70
> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>
> Fixes: bz#1808875

Change-Id: I7ed6108554ca379d532efb1a29b2de8085410b70
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>
Fixes: bz#1809440

Problem:
In a hyperconverged setup with granular-entry-heal enabled, if a file is
recreated while one of the bricks is down, and an index heal is triggered
(with the brick still down), entry-self heal was doing a spurious heal
with just the 2 good bricks. It was doing a post-op leading to removal
of the filename from .glusterfs/indices/entry-changes as well as
erroneous setting of afr xattrs on the parent. When the brick came up,
the xattrs were cleared, resulting in the renamed file not getting
healed and leading to gfid split-brain and EIO on the mount.

Fix:
Proceed with entry heal only when shd can connect to all bricks of the replica,
just like in data and metadata heal.

fixes: #1103
Change-Id: I916ae26ad1fabf259bc6362da52d433b7223b17e
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
(cherry picked from commit 06453d77d056fbaa393a137ca277a20e38d2f67e)

...if pending xattrs are zero for all children.

Problem:
If there are no pending xattrs and a metadata heal needs to be
performed, it can be possible that we end up with xattrs inadvertendly
deleted from all bricks, as explained in the  BZ.

Fix:
After picking one among the sources as the good copy, mark pending xattrs on
all sources to blame the sinks. Now even if this metadata heal fails midway,
a subsequent heal will still choose one of the valid sources that it
picked previously.

Updates: #1067
Change-Id: If1b050b70b0ad911e162c04db4d89b263e2b8d7b
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
(cherry picked from commit 2d5ba449e9200b16184b1e7fc84cabd015f1f779)

Problem:
We currently don't have a roll-back/undoing of post-ops if quorum is not met.
Though the FOP is still unwound with failure, the xattrs remain on the disk.
Due to these partial post-ops and partial heals (healing only when 2 bricks
are up), we can end up in metadata split-brain purely from the afr xattrs
point of view i.e each brick is blamed by atleast one of the others for
metadata. These scenarios are hit when there is frequent connect/disconnect
of the client/shd to the bricks.

Fix:
Pick a source based on the xattr values. If 2 bricks blame one, the blamed
one must be treated as sink. If there is no majority, all are sources. Once
we pick a source, self-heal will then do the heal instead of erroring out
due to split-brain.
This patch also adds restriction of all the bricks to be up to perform
metadata heal to avoid any metadata loss.

Removed the test case tests/bugs/replicate/bug-1468279-source-not-blaming-sinks.t
as it was doing metadata heal even when only 2 of 3 bricks were up.

Change-Id: I07a9d62f84ceda329dcab1f02a33aeed258dcb09
fixes: bz#1806931
Signed-off-by: karthik-us <ksubrahm@redhat.com>

Backport of https://review.gluster.org/#/c/glusterfs/+/23288/

...whenever shd is re-enabled after disabling or there is a change in
`cluster.heal-timeout`, without needing to restart shd or waiting for the
current `cluster.heal-timeout` seconds to expire.

See BZ 1743988 for more details.

Change-Id: Ia5ebd7c8e9f5b54cba3199c141fdd1af2f9b9bfe
fixes: bz#1807431
Reported-by: Glen Kiessling <glenk1973@hotmail.com>
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

Problem:
ec_getxattr_heal_cbk was called with NULL as second argument
in case heal was failing.
This function was dereferencing "cookie" argument which caused crash.

Solution:
Cookie is changed to carry the value that was supposed to be
stored in fop->data, so even in the case when fop is NULL in error
case, there won't be any NULL dereference.

Thanks to Xavi for the suggestion about the fix.

Change-Id: I0798000d5cadb17c3c2fbfa1baf77033ffc2bb8c
fixes: bz#1805057

When discard/truncate performs write fop, it should do so
after updating lock->good_mask to make sure readv happens
on the correct mask

fixes: bz#1805056
Change-Id: Idfef0bbcca8860d53707094722e6ba3f81c583b7
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

Problem:
when a file needs to be re-opened O_APPEND and O_EXCL
flags are not filtered in EC.

- O_APPEND should be filtered because EC doesn't send O_APPEND below EC for
open to make sure writes happen on the individual fragments instead of at the
end of the file.

- O_EXCL should be filtered because shd could have created the file so even
when file exists open should succeed

- O_CREAT should be filtered because open happens with gfid as parameter. So
open fop will create just the gfid which will lead to problems.

Fix:
Filter out these two flags in reopen.

Change-Id: Ia280470fcb5188a09caa07bf665a2a94bce23bc4
Fixes: bz#1805055
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

There are cases where fop->mask may have fop->healing added
and readv shouldn't be wound on fop->healing. To avoid this
always wind readv to lock->good_mask

fixes: bz#1805054
Change-Id: I2226ef0229daf5ff315d51e868b980ee48060b87
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

EC doesn't allow concurrent writes on overlapping areas, they are
serialized. However non-overlapping writes are serviced in parallel.
When a write is not aligned, EC first needs to read the entire chunk
from disk, apply the modified fragment and write it again.

The problem appears on sparse files because a write to an offset
implicitly creates data on offsets below it (so, in some way, they
are overlapping). For example, if a file is empty and we read 10 bytes
from offset 10, read() will return 0 bytes. Now, if we write one byte
at offset 1M and retry the same read, the system call will return 10
bytes (all containing 0's).

So if we have two writes, the first one at offset 10 and the second one
at offset 1M, EC will send both in parallel because they do not overlap.
However, the first one will try to read missing data from the first chunk
(i.e. offsets 0 to 9) to recombine the entire chunk and do the final write.
This read will happen in parallel with the write to 1M. What could happen
is that half of the bricks process the write before the read, and the
half do the read before the write. Some bricks will return 10 bytes of
data while the otherw will return 0 bytes (because the file on the brick
has not been expanded yet).

When EC tries to recombine the answers from the bricks, it can't, because
it needs more than half consistent answers to recover the data. So this
read fails with EIO error. This error is propagated to the parent write,
which is aborted and EIO is returned to the application.

The issue happened because EC assumed that a write to a given offset
implies that offsets below it exist.

This fix prevents the read of the chunk from bricks if the current size
of the file is smaller than the read chunk offset. This size is
correctly tracked, so this fixes the issue.

Also modifying ec-stripe.t file for Test #13 within it.
In this patch, if a file size is less than the offset we are writing, we
fill zeros in head and tail and do not consider it strip cache miss.
That actually make sense as we know what data that part holds and there is
no need of reading it from bricks.

Change-Id: Ic342e8c35c555b8534109e9314c9a0710b6225d6
Fixes: bz#1805053
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>