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2016-05-26ceph: handle interrupted ceph_writepage()Yan, Zheng1-4/+18
writepage() can be interrupted when it's called by direct memory reclaimer (the direct memory relaimer is killed). To avoid lossing data, we redirty the page. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: make ceph_update_writeable_page() uninterruptibleYan, Zheng1-1/+1
ceph_update_writeable_page() is used by ceph_write_begin(). It beaks atomicity of write operation if it's interruptible. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: handle -EAGAIN returned by ceph_update_writeable_page()Yan, Zheng1-13/+15
when ceph_update_writeable_page() return -EAGAIN, caller should lock the page and call ceph_update_writeable_page() again. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: make fault/page_mkwrite return VM_FAULT_OOM for -ENOMEMYan, Zheng1-20/+17
Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: block non-fatal signals for fault/page_mkwriteYan, Zheng1-27/+39
Fault and page_mkwrite are supposed to be uninterruptable. But they call ceph functions that are interruptible. So they should block signals before calling functions that are interruptible Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: make logical calculation functions return boolZhang Zhuoyu2-2/+2
This patch makes serverl logical caculation functions return bool to improve readability due to these particular functions only using 0/1 as their return value. No functional change. Signed-off-by: Zhang Zhuoyu <zhangzhuoyu@cmss.chinamobile.com>
2016-05-26ceph: tolerate bad i_size for symlink inodeYan, Zheng1-7/+15
A mds bug can cause symlink's size to be truncated to zero. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: improve fragtree change detectionYan, Zheng2-4/+21
check if number of splits in i_fragtree is equal to number of splits in mds reply Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: keep leaf frag when updating fragtreeYan, Zheng1-5/+23
Nodes in i_fragtree are sorted according to ceph_compare_frag(). It means frag node in i_fragtree always follow its direct parent node. To check if a leaf node is valid, we just need to check if it's child of previous split node. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: fix dir_auth check in ceph_fill_dirfrag()Yan, Zheng1-0/+3
-1 is CDIR_AUTH_PARENT, it means dir's auth mds is the same as inode's auth mds Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: don't assume frag tree splits in mds reply are sortedYan, Zheng1-0/+13
The algorithm that updates i_fragtree relies on that the frag tree splits in mds reply are of the same order of i_fragtree. This is not true because current MDS encodes frag tree splits in ascending order of (unsigned)frag_t. But nodes in i_fragtree are sorted according to ceph_frag_compare(). The fix is sort the frag tree splits first, then updates i_fragtree. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: fix inode reference leakYan, Zheng1-1/+1
Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: using hash value to compose dentry offsetYan, Zheng5-47/+135
If MDS sorts dentries in dirfrag in hash order, we use hash value to compose dentry offset. dentry offset is: (0xff << 52) | ((24 bits hash) << 28) | (the nth entry hash hash collision) This offset is stable across directory fragmentation. This alos means there is no need to reset readdir offset if directory get fragmented in the middle of readdir. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: don't forbid marking directory complete after forward seekYan, Zheng1-5/+0
Forward seek within same frag does not update fi->last_name, it will not affect contents of later readdir reply. So there is no need to forbid marking directory complete Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: record 'offset' for each entry of readdir resultYan, Zheng5-29/+59
This is preparation for using hash value as dentry 'offset' Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: define 'end/complete' in readdir reply as bit flagsYan, Zheng3-3/+8
Set a flag in readdir request, which indicates that client interprets 'end/complete' as bit flags. So that mds can reply additional flags in readdir reply. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: define struct for dir entry in readdir replyYan, Zheng4-52/+50
This avoids defining multiple arrays for entries in readdir reply Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: simplify 'offset in frag'Yan, Zheng2-13/+4
don't distinguish leftmost frag from other frags. always use 2 as first entry's offset. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: remove unnecessary checks in __dcache_readdirYan, Zheng1-2/+0
we never add snapdir and the hidden .ceph dir into readdir cache Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: search cache postion for dcache readdirYan, Zheng1-46/+83
use binary search to find cache index that corresponds to readdir postion. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: use CEPH_MDS_OP_RMXATTR request to remove xattrYan, Zheng1-6/+11
Setxattr with NULL value and XATTR_REPLACE flag should be equivalent to removexattr. But current MDS does not support deleting vxattrs through MDS_OP_SETXATTR request. The workaround is sending MDS_OP_RMXATTR request if setxattr actually removs xattr. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: report mount root in session metadataYan, Zheng3-15/+23
Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: don't show symlink target in debugfs/mdscYan, Zheng1-1/+1
symlink target is useless for debug and can be very long. It's annoying to show it in debugfs/mdsc. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: don't call truncate_pagecache in ceph_writepages_startYan, Zheng3-9/+38
truncate_pagecache() may decrease inode's reference. This can cause deadlock if inode's last reference is dropped and iput_final() wants to evict the inode. (evict() calls inode_wait_for_writeback(), which waits for ceph_writepages_start() to return). The fix is use work thead to truncate dirty pages. Also add 'forced umount' check to ceph_update_writeable_page(), which prevents new pages getting dirty. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: renew caps for read/write if mds session got killed.Yan, Zheng4-11/+93
When mds session gets killed, read/write operation may hang. Client waits for Frw caps, but mds does not know what caps client wants. To recover this, client sends an open request to mds. The request will tell mds what caps client wants. Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: CEPH_FEATURE_MDSENC supportYan, Zheng2-12/+36
Signed-off-by: Yan, Zheng <zyan@redhat.com>
2016-05-26ceph: multiple filesystem supportYan, Zheng2-0/+10
To access non-default filesystem, we just need to subscribe to mdsmap.<MDS_NAMESPACE_ID> and add a new mount option for mds namespace id. Signed-off-by: Yan, Zheng <zyan@redhat.com> [idryomov@gmail.com: switch to a new libceph API] Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: a major OSD client updateIlya Dryomov2-8/+8
This is a major sync up, up to ~Jewel. The highlights are: - per-session request trees (vs a global per-client tree) - per-session locking (vs a global per-client rwlock) - homeless OSD session - no ad-hoc global per-client lists - support for pool quotas - foundation for watch/notify v2 support - foundation for map check (pool deletion detection) support The switchover is incomplete: lingering requests can be setup and teared down but aren't ever reestablished. This functionality is restored with the introduction of the new lingering infrastructure (ceph_osd_linger_request, linger_work, etc) in a later commit. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: redo callbacks and factor out MOSDOpReply decodingIlya Dryomov2-2/+3
If you specify ACK | ONDISK and set ->r_unsafe_callback, both ->r_callback and ->r_unsafe_callback(true) are called on ack. This is very confusing. Redo this so that only one of them is called: ->r_unsafe_callback(true), on ack ->r_unsafe_callback(false), on commit or ->r_callback, on ack|commit Decode everything in decode_MOSDOpReply() to reduce clutter. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: drop msg argument from ceph_osdc_callback_tIlya Dryomov2-9/+7
finish_read(), its only user, uses it to get to hdr.data_len, which is what ->r_result is set to on success. This gains us the ability to safely call callbacks from contexts other than reply, e.g. map check. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: switch to calc_target(), part 2Ilya Dryomov2-23/+9
The crux of this is getting rid of ceph_osdc_build_request(), so that MOSDOp can be encoded not before but after calc_target() calculates the actual target. Encoding now happens within ceph_osdc_start_request(). Also nuked is the accompanying bunch of pointers into the encoded buffer that was used to update fields on each send - instead, the entire front is re-encoded. If we want to support target->name_len != base->name_len in the future, there is no other way, because oid is surrounded by other fields in the encoded buffer. Encoding OSD ops and adding data items to the request message were mixed together in osd_req_encode_op(). While we want to re-encode OSD ops, we don't want to add duplicate data items to the message when resending, so all call to ceph_osdc_msg_data_add() are factored out into a new setup_request_data(). Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: introduce ceph_osd_request_target, calc_target()Ilya Dryomov2-2/+2
Introduce ceph_osd_request_target, containing all mapping-related fields of ceph_osd_request and calc_target() for calculating mappings and populating it. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: rename ceph_calc_pg_primary()Ilya Dryomov1-1/+1
Rename ceph_calc_pg_primary() to ceph_pg_to_acting_primary() to emphasise that it returns acting primary. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: rename ceph_oloc_oid_to_pg()Ilya Dryomov1-1/+1
Rename ceph_oloc_oid_to_pg() to ceph_object_locator_to_pg(). Emphasise that returned is raw PG and return -ENOENT instead of -EIO if the pool doesn't exist. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: DEFINE_RB_FUNCS macroIlya Dryomov1-41/+13
Given struct foo { u64 id; struct rb_node bar_node; }; generate insert_bar(), erase_bar() and lookup_bar() functions with DEFINE_RB_FUNCS(bar, struct foo, id, bar_node) The key is assumed to be an integer (u64, int, etc), compared with < and >. nodefld has to be initialized with RB_CLEAR_NODE(). Start using it for MDS, MON and OSD requests and OSD sessions. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: variable-sized ceph_object_idIlya Dryomov3-6/+4
Currently ceph_object_id can hold object names of up to 100 (CEPH_MAX_OID_NAME_LEN) characters. This is enough for all use cases, expect one - long rbd image names: - a format 1 header is named "<imgname>.rbd" - an object that points to a format 2 header is named "rbd_id.<imgname>" We operate on these potentially long-named objects during rbd map, and, for format 1 images, during header refresh. (A format 2 header name is a small system-generated string.) Lift this 100 character limit by making ceph_object_id be able to point to an externally-allocated string. Apart from being able to work with almost arbitrarily-long named objects, this allows us to reduce the size of ceph_object_id from >100 bytes to 64 bytes. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: move message allocation out of ceph_osdc_alloc_request()Ilya Dryomov2-0/+15
The size of ->r_request and ->r_reply messages depends on the size of the object name (ceph_object_id), while the size of ceph_osd_request is fixed. Move message allocation into a separate function that would have to be called after ceph_object_id and ceph_object_locator (which is also going to become variable in size with RADOS namespaces) have been filled in: req = ceph_osdc_alloc_request(...); <fill in req->r_base_oid> <fill in req->r_base_oloc> ceph_osdc_alloc_messages(req); Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-26libceph: make ceph_osdc_put_request() accept NULLIlya Dryomov1-6/+3
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2016-05-14Merge branch 'for-linus' of ↵Linus Torvalds6-52/+110
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs fixes from Al Viro: "Overlayfs fixes from Miklos, assorted fixes from me. Stable fodder of varying severity, all sat in -next for a while" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: ovl: ignore permissions on underlying lookup vfs: add lookup_hash() helper vfs: rename: check backing inode being equal vfs: add vfs_select_inode() helper get_rock_ridge_filename(): handle malformed NM entries ecryptfs: fix handling of directory opening atomic_open(): fix the handling of create_error fix the copy vs. map logics in blk_rq_map_user_iov() do_splice_to(): cap the size before passing to ->splice_read()
2016-05-13Merge branch 'for-4.6-fixes' of ↵Linus Torvalds2-3/+18
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: "During v4.6-rc1 cgroup namespace support was merged. There is an issue where it's impossible to tell whether a given cgroup mount point is bind mounted or namespaced. Serge has been working on the issue but it took longer than expected to resolve, so the late pull request. Given that it's a completely new feature and the patches don't touch anything else, the risk seems acceptable. However, if this is too late, an alternative is plugging new cgroup ns creation for v4.6 and retrying for v4.7" * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fix compile warning kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry call cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces kernfs_path_from_node_locked: don't overwrite nlen
2016-05-12ocfs2: fix posix_acl_create deadlockJunxiao Bi6-48/+77
Commit 702e5bc68ad2 ("ocfs2: use generic posix ACL infrastructure") refactored code to use posix_acl_create. The problem with this function is that it is not mindful of the cluster wide inode lock making it unsuitable for use with ocfs2 inode creation with ACLs. For example, when used in ocfs2_mknod, this function can cause deadlock as follows. The parent dir inode lock is taken when calling posix_acl_create -> get_acl -> ocfs2_iop_get_acl which takes the inode lock again. This can cause deadlock if there is a blocked remote lock request waiting for the lock to be downconverted. And same deadlock happened in ocfs2_reflink. This fix is to revert back using ocfs2_init_acl. Fixes: 702e5bc68ad2 ("ocfs2: use generic posix ACL infrastructure") Signed-off-by: Tariq Saeed <tariq.x.saeed@oracle.com> Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joseph Qi <joseph.qi@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-12ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hangJunxiao Bi3-2/+27
Commit 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()") introduced this issue. ocfs2_setattr called by chmod command holds cluster wide inode lock when calling posix_acl_chmod. This latter function in turn calls ocfs2_iop_get_acl and ocfs2_iop_set_acl. These two are also called directly from vfs layer for getfacl/setfacl commands and therefore acquire the cluster wide inode lock. If a remote conversion request comes after the first inode lock in ocfs2_setattr, OCFS2_LOCK_BLOCKED will be set. And this will cause the second call to inode lock from the ocfs2_iop_get_acl() to block indefinetly. The deleted version of ocfs2_acl_chmod() calls __posix_acl_chmod() which does not call back into the filesystem. Therefore, we restore ocfs2_acl_chmod(), modify it slightly for locking as needed, and use that instead. Fixes: 743b5f1434f5 ("ocfs2: take inode lock in ocfs2_iop_set/get_acl()") Signed-off-by: Tariq Saeed <tariq.x.saeed@oracle.com> Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joseph Qi <joseph.qi@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-12kernfs: kernfs_sop_show_path: don't return 0 after seq_dentry callSerge E. Hallyn1-1/+2
Our caller expects 0 on success, not >0. This fixes a bug in the patch cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces where /sys does not show up in mountinfo, breaking criu. Thanks for catching this, Andrei. Reported-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-05-11Merge branch 'ovl-fixes' into for-linusAl Viro274-2566/+2974
2016-05-10ovl: ignore permissions on underlying lookupMiklos Szeredi1-3/+1
Generally permission checking is not necessary when overlayfs looks up a dentry on one of the underlying layers, since search permission on base directory was already checked in ovl_permission(). More specifically using lookup_one_len() causes a problem when the lower directory lacks search permission for a specific user while the upper directory does have search permission. Since lookups are cached, this causes inconsistency in behavior: success depends on who did the first lookup. So instead use lookup_hash() which doesn't do the permission check. Reported-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-10vfs: add lookup_hash() helperMiklos Szeredi1-5/+28
Overlayfs needs lookup without inode_permission() and already has the name hash (in form of dentry->d_name on overlayfs dentry). It also doesn't support filesystems with d_op->d_hash() so basically it only needs the actual hashed lookup from lookup_one_len_unlocked() So add a new helper that does unlocked lookup of a hashed name. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-10vfs: rename: check backing inode being equalMiklos Szeredi1-1/+5
If a file is renamed to a hardlink of itself POSIX specifies that rename(2) should do nothing and return success. This condition is checked in vfs_rename(). However it won't detect hard links on overlayfs where these are given separate inodes on the overlayfs layer. Overlayfs itself detects this condition and returns success without doing anything, but then vfs_rename() will proceed as if this was a successful rename (detach_mounts(), d_move()). The correct thing to do is to detect this condition before even calling into overlayfs. This patch does this by calling vfs_select_inode() to get the underlying inodes. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org> # v4.2+
2016-05-10vfs: add vfs_select_inode() helperMiklos Szeredi1-8/+4
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org> # v4.2+
2016-05-09Revert "proc/base: make prompt shell start from new line after executing ↵Robin Humble1-1/+1
"cat /proc/$pid/wchan"" This reverts the 4.6-rc1 commit 7e2bc81da333 ("proc/base: make prompt shell start from new line after executing "cat /proc/$pid/wchan") because it breaks /proc/$PID/whcan formatting in ps and top. Revert also because the patch is inconsistent - it adds a newline at the end of only the '0' wchan, and does not add a newline when /proc/$PID/wchan contains a symbol name. eg. $ ps -eo pid,stat,wchan,comm PID STAT WCHAN COMMAND ... 1189 S - dbus-launch 1190 Ssl 0 dbus-daemon 1198 Sl 0 lightdm 1299 Ss ep_pol systemd 1301 S - (sd-pam) 1304 Ss wait sh Signed-off-by: Robin Humble <plaguedbypenguins@gmail.com> Cc: Minfei Huang <mnfhuang@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-09cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespacesSerge E. Hallyn1-0/+14
Patch summary: When showing a cgroupfs entry in mountinfo, show the path of the mount root dentry relative to the reader's cgroup namespace root. Short explanation (courtesy of mkerrisk): If we create a new cgroup namespace, then we want both /proc/self/cgroup and /proc/self/mountinfo to show cgroup paths that are correctly virtualized with respect to the cgroup mount point. Previous to this patch, /proc/self/cgroup shows the right info, but /proc/self/mountinfo does not. Long version: When a uid 0 task which is in freezer cgroup /a/b, unshares a new cgroup namespace, and then mounts a new instance of the freezer cgroup, the new mount will be rooted at /a/b. The root dentry field of the mountinfo entry will show '/a/b'. cat > /tmp/do1 << EOF mount -t cgroup -o freezer freezer /mnt grep freezer /proc/self/mountinfo EOF unshare -Gm bash /tmp/do1 > 330 160 0:34 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,freezer > 355 133 0:34 /a/b /mnt rw,relatime - cgroup freezer rw,freezer The task's freezer cgroup entry in /proc/self/cgroup will simply show '/': grep freezer /proc/self/cgroup 9:freezer:/ If instead the same task simply bind mounts the /a/b cgroup directory, the resulting mountinfo entry will again show /a/b for the dentry root. However in this case the task will find its own cgroup at /mnt/a/b, not at /mnt: mount --bind /sys/fs/cgroup/freezer/a/b /mnt 130 25 0:34 /a/b /mnt rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,freezer In other words, there is no way for the task to know, based on what is in mountinfo, which cgroup directory is its own. Example (by mkerrisk): First, a little script to save some typing and verbiage: echo -e "\t/proc/self/cgroup:\t$(cat /proc/self/cgroup | grep freezer)" cat /proc/self/mountinfo | grep freezer | awk '{print "\tmountinfo:\t\t" $4 "\t" $5}' Create cgroup, place this shell into the cgroup, and look at the state of the /proc files: 2653 2653 # Our shell 14254 # cat(1) /proc/self/cgroup: 10:freezer:/a/b mountinfo: / /sys/fs/cgroup/freezer Create a shell in new cgroup and mount namespaces. The act of creating a new cgroup namespace causes the process's current cgroups directories to become its cgroup root directories. (Here, I'm using my own version of the "unshare" utility, which takes the same options as the util-linux version): Look at the state of the /proc files: /proc/self/cgroup: 10:freezer:/ mountinfo: / /sys/fs/cgroup/freezer The third entry in /proc/self/cgroup (the pathname of the cgroup inside the hierarchy) is correctly virtualized w.r.t. the cgroup namespace, which is rooted at /a/b in the outer namespace. However, the info in /proc/self/mountinfo is not for this cgroup namespace, since we are seeing a duplicate of the mount from the old mount namespace, and the info there does not correspond to the new cgroup namespace. However, trying to create a new mount still doesn't show us the right information in mountinfo: # propagating to other mountns /proc/self/cgroup: 7:freezer:/ mountinfo: /a/b /mnt/freezer The act of creating a new cgroup namespace caused the process's current freezer directory, "/a/b", to become its cgroup freezer root directory. In other words, the pathname directory of the directory within the newly mounted cgroup filesystem should be "/", but mountinfo wrongly shows us "/a/b". The consequence of this is that the process in the cgroup namespace cannot correctly construct the pathname of its cgroup root directory from the information in /proc/PID/mountinfo. With this patch, the dentry root field in mountinfo is shown relative to the reader's cgroup namespace. So the same steps as above: /proc/self/cgroup: 10:freezer:/a/b mountinfo: / /sys/fs/cgroup/freezer /proc/self/cgroup: 10:freezer:/ mountinfo: /../.. /sys/fs/cgroup/freezer /proc/self/cgroup: 10:freezer:/ mountinfo: / /mnt/freezer cgroup.clone_children freezer.parent_freezing freezer.state tasks cgroup.procs freezer.self_freezing notify_on_release 3164 2653 # First shell that placed in this cgroup 3164 # Shell started by 'unshare' 14197 # cat(1) Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com> Tested-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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