The addition of bal_rank_mask with encoding version 17 was merged
into ceph.git in Oct 2022 and made it into v18.2.0 release normally.
A few months later, the much delayed addition of max_xattr_size got
merged, also with encoding version 17, placed before bal_rank_mask
in the encoding -- but it didn't make v18.2.0 release.
The way this ended up being resolved on the MDS side is that
bal_rank_mask will continue to be encoded in version 17 while
max_xattr_size is now encoded in version 18. This does mean that
older kernels will misdecode version 17, but this is also true for
v18.2.0 and v18.2.1 clients in userspace.
The best we can do is backport this adjustment -- see ceph.git
commit 78abfeaff27fee343fb664db633de5b221699a73 for details.
[ idryomov: changelog ]
Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/64440
Fixes: d93231a6bc ("ceph: prevent a client from exceeding the MDS maximum xattr size")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@ibm.com>
Reviewed-by: Venky Shankar <vshankar@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The mdsmap.h is only used by CephFS, so move it to fs/ceph.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Multiple CephFS mounts on a host is increasingly common so
disambiguating messages like this is necessary and will make it easier
to debug issues.
At the same this will improve the debug logs to make them easier to
troubleshooting issues, such as print the ino# instead only printing
the memory addresses of the corresponding inodes and print the dentry
names instead of the corresponding memory addresses for the dentry,etc.
Link: https://tracker.ceph.com/issues/61590
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
We will use the 'mdsc' to get the global_id in the following commits.
Link: https://tracker.ceph.com/issues/61590
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This is a simple mechanical transformation done by:
@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
(E)
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@
((T)get_random_u32()@p & (LITERAL))
// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@
value = None
if literal.startswith('0x'):
value = int(literal, 16)
elif literal[0] in '123456789':
value = int(literal, 10)
if value is None:
print("I don't know how to handle %s" % (literal))
cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
The MDS tries to enforce a limit on the total key/values in extended
attributes. However, this limit is enforced only if doing a synchronous
operation (MDS_OP_SETXATTR) -- if we're buffering the xattrs, the MDS
doesn't have a chance to enforce these limits.
This patch adds support for decoding the xattrs maximum size setting that is
distributed in the mdsmap. Then, when setting an xattr, the kernel client
will revert to do a synchronous operation if that maximum size is exceeded.
While there, fix a dout() that would trigger a printk warning:
[ 98.718078] ------------[ cut here ]------------
[ 98.719012] precision 65536 too large
[ 98.719039] WARNING: CPU: 1 PID: 3755 at lib/vsprintf.c:2703 vsnprintf+0x5e3/0x600
...
Link: https://tracker.ceph.com/issues/55725
Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
If the max_mds is decreased in a cephfs cluster, there is a window
of time before the MDSs are removed. If a map goes out during this
period, the mdsmap may show the decreased max_mds but still shows
those MDSes as in or in the export target list.
Ensure that we don't fail the map decode in that case.
Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/52436
Fixes: d517b3983d ("ceph: reconnect to the export targets on new mdsmaps")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
In the case where the export MDS has crashed just after the EImportStart
journal is flushed, a standby MDS takes over for it and when replaying
the EImportStart journal the MDS will wait the client to reconnect. That
may never happen because the client may not have registered or opened
the sessions yet.
When receiving a new map, ensure we reconnect to valid export targets as
well if their sessions don't exist yet.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
kcalloc() is called to allocate memory for m->m_info, and if it fails,
ceph_mdsmap_destroy() behind the label out_err will be called:
ceph_mdsmap_destroy(m);
In ceph_mdsmap_destroy(), m->m_info is dereferenced through:
kfree(m->m_info[i].export_targets);
To fix this possible null-pointer dereference, check m->m_info before the
for loop to free m->m_info[i].export_targets.
[ jlayton: fix up whitespace damage
only kfree(m->m_info) if it's non-NULL ]
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
In preparation for msgr2, make the cluster send us maps with addrvecs
including both LEGACY and MSGR2 addrs instead of a single LEGACY addr.
This means advertising support for SERVER_NAUTILUS and also some older
features: SERVER_MIMIC, MONENC and MONNAMES.
MONNAMES and MONENC are actually pre-argonaut, we just never updated
ceph_monmap_decode() for them. Decoding is unconditional, see commit
23c625ce30 ("libceph: assume argonaut on the server side").
SERVER_MIMIC doesn't bear any meaning for the kernel client.
Since ceph_decode_entity_addrvec() is guarded by encoding version
checks (and in msgr2 case it is guarded implicitly by the fact that
server is speaking msgr2), we assume MSG_ADDR2 for it.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
While the MDS cluster is unstable and changing state the client may get
mdsmap updates that will trigger warnings:
[144692.478400] ceph: mdsmap_decode got incorrect state(up:standby-replay)
[144697.489552] ceph: mdsmap_decode got incorrect state(up:standby-replay)
[144697.489580] ceph: mdsmap_decode got incorrect state(up:standby-replay)
This patch downgrades these warnings to debug, as they may flood the logs
if the cluster is unstable for a while.
Signed-off-by: Luis Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Fix build warnings:
fs/ceph/mdsmap.c: In function ‘ceph_mdsmap_decode’:
fs/ceph/mdsmap.c:192:7: warning: variable ‘info_cv’ set but not used [-Wunused-but-set-variable]
fs/ceph/mdsmap.c:177:7: warning: variable ‘state_seq’ set but not used [-Wunused-but-set-variable]
fs/ceph/mdsmap.c:123:15: warning: variable ‘mdsmap_cv’ set but not used [-Wunused-but-set-variable]
Note that p is increased in ceph_decode_*.
Signed-off-by: Jia Yang <jiayang5@huawei.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The m_num_mds here is actually the number for MDSs which are in
up:active status, and it will be duplicated to m_num_active_mds,
so remove it.
Add possible_max_rank to the mdsmap struct and this will be
the correctly possible largest rank boundary.
Remove the special case for one mds in __mdsmap_get_random_mds(),
because the validate mds rank may not always be 0.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Even the MDS is in up:active state, but it also maybe laggy. Here
will skip the laggy MDSs.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
In case the max_mds > 1 in MDS cluster and there is no any standby
MDS and all the max_mds MDSs are in up:active state, if one of the
up:active MDSs is dead, the m->m_num_laggy in kclient will be 1.
Then the mount will fail without considering other healthy MDSs.
There manybe some MDSs still "in" the cluster but not in up:active
state, we will ignore them. Only when all the up:active MDSs in
the cluster are laggy will treat the cluster as not be available.
In case decreasing the max_mds, the cluster will not stop the extra
up:active MDSs immediately and there will be a latency. During it
the up:active MDS number will be larger than the max_mds, so later
the m_info memories will 100% be reallocated.
Here will pick out the up:active MDSs as the m_num_mds and allocate
the needed memories once.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Show the laggy state.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
For example, if we have 5 mds in the mdsmap and the states are:
m_info[5] --> [-1, 1, -1, 1, 1]
If we get a random number 1, then we should get the mds index 3 as
expected, but actually we will get index 2, which the state is -1.
The issue is that the for loop increment will advance past any "up"
MDS that was found during the while loop search.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
GCC9 is throwing a lot of warnings about unaligned accesses by
callers of ceph_pr_addr. All of the current callers are passing a
pointer to the sockaddr inside struct ceph_entity_addr.
Fix it to take a pointer to a struct ceph_entity_addr instead,
and then have the function make a copy of the sockaddr before
printing it.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
There is redundant assighment of variable i in
ceph_mdsmap_get_random_mds(), just remvoe it.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The script “checkpatch.pl” pointed information out like the following.
Comparison to NULL could be written ...
Thus fix the affected source code places.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
mdsmap::m_max_mds is the expected count of active mds. It's not the
max rank of active mds. User can decrease mdsmap::m_max_mds, but does
not stop mds whose rank >= mdsmap::m_max_mds.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Update the last pr_warning callsites in fs branch
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Sage Weil <sage@inktank.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I introduced a new temporary variable "info" instead of
"m->m_info[mds]". Also I reversed the if condition and pulled
everything in one indent level.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This patch makes the following improvements to the error handling
in the ceph_mdsmap_decode function:
- Add a NULL check for return value from kcalloc
- Make use of the variable err
Signed-off-by: Emil Goode <emilgoode@gmail.com>
Signed-off-by: Sage Weil <sage@inktank.com>
We don't need to use up entropy to choose an mds,
so use prandom_u32() to get a pseudo-random number.
Also, we don't need to choose a random mds if only
one mds is available, so add special casing for the
common case.
Fixes http://tracker.ceph.com/issues/3579
Signed-off-by: Sam Lang <sam.lang@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
Support (and require) the PGID64, PGPOOL3, and OSDENC protocol features.
These have been present in ceph.git since v0.42, Feb 2012. Require these
features to simplify support; nobody is running older userspace.
Note that the new request and reply encoding is still not in place, so the new
code is not yet functional.
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This factors out protocol and low-level storage parts of ceph into a
separate libceph module living in net/ceph and include/linux/ceph. This
is mostly a matter of moving files around. However, a few key pieces
of the interface change as well:
- ceph_client becomes ceph_fs_client and ceph_client, where the latter
captures the mon and osd clients, and the fs_client gets the mds client
and file system specific pieces.
- Mount option parsing and debugfs setup is correspondingly broken into
two pieces.
- The mon client gets a generic handler callback for otherwise unknown
messages (mds map, in this case).
- The basic supported/required feature bits can be expanded (and are by
ceph_fs_client).
No functional change, aside from some subtle error handling cases that got
cleaned up in the refactoring process.
Signed-off-by: Sage Weil <sage@newdream.net>
The mds map now uses the global_id as the 'key' (instead of the addr,
which was a poor choice).
This is protocol change.
Signed-off-by: Sage Weil <sage@newdream.net>
We exchange struct ceph_entity_addr over the wire and store it on disk.
The sockaddr_storage.ss_family field, however, is host endianness. So,
fix ss_family endianness to big endian when sending/receiving over the
wire.
Signed-off-by: Sage Weil <sage@newdream.net>
The MDS (metadata server) client is responsible for submitting
requests to the MDS cluster and parsing the response. We decide which
MDS to submit each request to based on cached information about the
current partition of the directory hierarchy across the cluster. A
stateful session is opened with each MDS before we submit requests to
it, and a mutex is used to control the ordering of messages within
each session.
An MDS request may generate two responses. The first indicates the
operation was a success and returns any result. A second reply is
sent when the operation commits to disk. Note that locking on the MDS
ensures that the results of updates are visible only to the updating
client before the operation commits. Requests are linked to the
containing directory so that an fsync will wait for them to commit.
If an MDS fails and/or recovers, we resubmit requests as needed. We
also reconnect existing capabilities to a recovering MDS to
reestablish that shared session state. Old dentry leases are
invalidated.
Signed-off-by: Sage Weil <sage@newdream.net>
Xiubo Li