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2018-01-24CIFS: SMBD: Upper layer destroys SMB Direct session on shutdown or umountLong Li
When upper layer wants to umount, make it call shutdown on transport when SMB Direct is used. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-01-24CIFS: SMBD: Implement function to destroy a SMB Direct connectionLong Li
Add function to tear down a SMB Direct connection. This is used by upper layer to free all SMB Direct connection and transport resources. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-01-24CIFS: SMBD: Upper layer reconnects to SMB Direct sessionLong Li
Do a reconnect on SMB Direct when it is used as the connection. Reconnect can happen for many reasons and it's mostly the decision of SMB2 upper layer. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24CIFS: SMBD: Implement function to reconnect to a SMB Direct transportLong Li
Add function to implement a reconnect to SMB Direct. This involves tearing down the current connection and establishing/negotiating a new connection. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-01-24CIFS: SMBD: Upper layer connects to SMBDirect sessionLong Li
When "rdma" is specified in the mount option, make CIFS connect to SMB Direct. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
2018-01-24cifs: fix build errors for SMB_DIRECTRandy Dunlap
Prevent build errors when CIFS=y and INFINIBAND=m. fs/cifs/smbdirect.o: In function `smbd_qp_async_error_upcall': smbdirect.c:(.text+0x28c): undefined reference to `ib_event_msg' fs/cifs/smbdirect.o: In function `smbd_destroy_rdma_work': smbdirect.c:(.text+0xfde): undefined reference to `ib_drain_qp' smbdirect.c:(.text+0xfea): undefined reference to `rdma_destroy_qp' smbdirect.c:(.text+0x12a0): undefined reference to `ib_free_cq' smbdirect.c:(.text+0x12ac): undefined reference to `ib_free_cq' smbdirect.c:(.text+0x12b8): undefined reference to `ib_dealloc_pd' smbdirect.c:(.text+0x12c4): undefined reference to `rdma_destroy_id' fs/cifs/smbdirect.o: In function `_smbd_get_connection': smbdirect.c:(.text+0x168c): undefined reference to `rdma_create_id' smbdirect.c:(.text+0x1713): undefined reference to `rdma_resolve_addr' smbdirect.c:(.text+0x1780): undefined reference to `rdma_resolve_route' smbdirect.c:(.text+0x17e3): undefined reference to `rdma_destroy_id' smbdirect.c:(.text+0x183d): undefined reference to `rdma_destroy_id' smbdirect.c:(.text+0x199d): undefined reference to `ib_alloc_cq' smbdirect.c:(.text+0x19d9): undefined reference to `ib_alloc_cq' smbdirect.c:(.text+0x1a89): undefined reference to `rdma_create_qp' smbdirect.c:(.text+0x1b3c): undefined reference to `rdma_connect' smbdirect.c:(.text+0x2538): undefined reference to `rdma_destroy_qp' smbdirect.c:(.text+0x2549): undefined reference to `ib_free_cq' smbdirect.c:(.text+0x255a): undefined reference to `ib_free_cq' smbdirect.c:(.text+0x2563): undefined reference to `ib_dealloc_pd' smbdirect.c:(.text+0x256c): undefined reference to `rdma_destroy_id' smbdirect.c:(.text+0x25f0): undefined reference to `__ib_alloc_pd' smbdirect.c:(.text+0x26bb): undefined reference to `rdma_disconnect' fs/cifs/smbdirect.o: In function `smbd_disconnect_rdma_work': smbdirect.c:(.text+0x62): undefined reference to `rdma_disconnect' Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Steve French <sfrench@samba.org> Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org (moderated for non-subscribers) Signed-off-by: Steve French <smfrench@gmail.com>
2018-01-24cifs: Fix missing put_xid in cifs_file_strict_mmapMatthew Wilcox
If cifs_zap_mapping() returned an error, we would return without putting the xid that we got earlier. Restructure cifs_file_strict_mmap() and cifs_file_mmap() to be more similar to each other and have a single point of return that always puts the xid. Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> CC: Stable <stable@vger.kernel.org>
2018-01-24CIFS: SMBD: export protocol initial valuesLong Li
For use-configurable SMB Direct protocol values, export them to /proc/fs/cifs. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24CIFS: SMBD: Implement function to create a SMB Direct connectionLong Li
The upper layer calls this function to connect to peer through SMB Direct. Each SMB Direct connection is based on a RDMA RC Queue Pair. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24CIFS: SMBD: Establish SMB Direct connectionLong Li
Add code to implement the core functions to establish a SMB Direct connection. 1. Establish an RDMA connection to SMB server. 2. Negotiate and setup SMB Direct protocol. 3. Implement idle connection timer and credit management. SMB Direct is enabled by setting CONFIG_CIFS_SMB_DIRECT. Add to Makefile to enable building SMB Direct. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24CIFS: SMBD: Add SMB Direct protocol initial values and constantsLong Li
To prepare for protocol implementation, add constants and user-configurable values for the SMB Direct protocol. Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Ronnie Sahlberg <lsahlber.redhat.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24CIFS: SMBD: Add rdma mount optionLong Li
Add "rdma" to CIFS mount options to connect to SMB Direct. Add checks to validate this is used on SMB 3.X dialects. To connect to SMBDirect, use "mount.cifs -o rdma,vers=3.x". At the time of this patch, 3.x can be 3.0, 3.02 or 3.1.1. Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Ronnie Sahlberg <lsahlber.redhat.com>
2018-01-24CIFS: SMBD: Introduce kernel config option CONFIG_CIFS_SMB_DIRECTLong Li
Build SMB Direct code when this option is set. Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Ronnie Sahlberg <lsahlber.redhat.com>
2018-01-24CIFS: SMBD: Add parameter rdata to smb2_new_read_reqLong Li
This patch is for preparing upper layer for doing SMB read via RDMA write. When we assemble the SMB read packet header, we need to know the I/O layout if this request is to use a RDMA write. rdata has all the information we need for memory registration. Add rdata to smb2_new_read_req. Signed-off-by: Long Li <longli@microsoft.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Ronnie Sahlberg <lsahlber.redhat.com>
2018-01-24cifs: avoid a kmalloc in smb2_send_recv/SendReceive2 for the common caseRonnie Sahlberg
In both functions, use an array of 8 (arbitrary but should be big enough for all current uses) iov and avoid having to kmalloc the array for the common case. If 8 is too small, then fall back to the original behaviour and use kmalloc/kfree. This should not change any behaviour but should save us a tiny amount of cpu cycles. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove small_smb2_initRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_lease_ackRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove unused variable from SMB2_readRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
2018-01-24cifs: remove rfc1002 header from smb2_oplock_break we get from serverRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_query_info_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_query_directory_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_set_info_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2 read/write requestsRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_lock_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
2018-01-24cifs: remove rfc1002 header from smb2_flush_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_create_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
2018-01-24cifs: remove rfc1002 header from smb2_sess_setup_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_tree_connect_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_echo_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_ioctl_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_close_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_tree_disconnect_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_logoff_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
2018-01-24cifs: remove rfc1002 header from smb2_negotiate_reqRonnie Sahlberg
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
2018-01-24cifs: Add smb2_send_recvRonnie Sahlberg
This function is similar to SendReceive2 except it does not expect a 4 byte rfc1002 length header in the first io vector. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: Steve French <smfrench@gmail.com>
2018-01-24lockd: Fix server refcountingTrond Myklebust
The server shouldn't actually delete the struct nlm_host until it hits the garbage collector. In order to make that work correctly with the refcount API, we can bump the refcount by one, and then use refcount_dec_if_one() in the garbage collector. Signed-off-by: Trond Myklebust <trondmy@gmail.com> Acked-by: J. Bruce Fields <bfields@fieldses.org>
2018-01-24Btrfs: fix stale entries in readdirJosef Bacik
In fixing the readdir+pagefault deadlock I accidentally introduced a stale entry regression in readdir. If we get close to full for the temporary buffer, and then skip a few delayed deletions, and then try to add another entry that won't fit, we will emit the entries we found and retry. Unfortunately we delete entries from our del_list as we find them, assuming we won't need them. However our pos will be with whatever our last entry was, which could be before the delayed deletions we skipped, so the next search will add the deleted entries back into our readdir buffer. So instead don't delete entries we find in our del_list so we can make sure we always find our delayed deletions. This is a slight perf hit for readdir with lots of pending deletions, but hopefully this isn't a common occurrence. If it is we can revist this and optimize it. cc: stable@vger.kernel.org Fixes: 23b5ec74943f ("btrfs: fix readdir deadlock with pagefault") Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
2018-01-24ovl: wire up NFS export operationsAmir Goldstein
Now that NFS export operations are implemented, enable overlayfs NFS export support if the "nfs_export" feature is enabled. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: lookup indexed ancestor of lower dirAmir Goldstein
ovl_lookup_real() in lower layer walks back lower parents to find the topmost indexed parent. If an indexed ancestor is found before reaching lower layer root, ovl_lookup_real() is called recursively with upper layer to walk back from indexed upper to the topmost connected/hashed upper parent (or up to root). ovl_lookup_real() in upper layer then walks forward to connect the topmost upper overlay dir dentry and ovl_lookup_real() in lower layer continues to walk forward to connect the decoded lower overlay dir dentry. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: lookup connected ancestor of dir in inode cacheAmir Goldstein
Decoding a dir file handle requires walking backward up to layer root and for lower dir also checking the index to see if any of the parents have been copied up. Lookup overlay ancestor dentry in inode/dentry cache by decoded real parents to shortcut looking up all the way back to layer root. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: hash non-indexed dir by upper inode for NFS exportAmir Goldstein
Non-indexed upper dirs are encoded as upper file handles. When NFS export is enabled, hash non-indexed directory inodes by upper inode, so we can find them in inode cache using the decoded upper inode. When NFS export is disabled, directories are not indexed on copy up, so hash non-indexed directory inodes by origin inode, the same hash key that is used before copy up. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode pure lower dir file handlesAmir Goldstein
Similar to decoding a pure upper dir file handle, decoding a pure lower dir file handle is implemented by looking an overlay dentry of the same path as the pure lower path and verifying that the overlay dentry's real lower matches the decoded real lower file handle. Unlike the case of upper dir file handle, the lookup of overlay path by lower real path can fail or find a mismatched overlay dentry if any of the lower parents have been copied up and renamed. To address this case we will need to check if any of the lower parents are indexed. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode indexed dir file handlesAmir Goldstein
Decoding an indexed dir file handle is done by looking up the file handle in index dir by name and then decoding the upper dir from the index origin file handle. The decoded upper path is used to lookup an overlay dentry of the same path. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode lower file handles of unlinked but open filesAmir Goldstein
Lookup overlay inode in cache by origin inode, so we can decode a file handle of an open file even if the index has a whiteout index entry to mark this overlay inode was unlinked. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode indexed non-dir file handlesAmir Goldstein
Decoding an indexed non-dir file handle is similar to decoding a lower non-dir file handle, but additionally, we lookup the file handle in index dir by name to find the real upper inode. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode lower non-dir file handlesAmir Goldstein
Decoding a lower non-dir file handle is done by decoding the lower dentry from underlying lower fs, finding or allocating an overlay inode that is hashed by the real lower inode and instantiating an overlay dentry with that inode. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: encode lower file handlesAmir Goldstein
For indexed or lower non-dir, encode a non-connectable lower file handle from origin inode. For indexed or lower dir, when ofs->numlower == 1, encode a lower file handle from lower dir. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: copy up before encoding non-connectable dir file handleAmir Goldstein
Decoding a merge dir, whose origin's parent is under a redirected lower dir is not always possible. As a simple aproximation, we do not encode lower dir file handles when overlay has multiple lower layers and origin is below the topmost lower layer. We should later relax this condition and copy up only the parent that is under a redirected lower. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: encode non-indexed upper file handlesAmir Goldstein
We only need to encode origin if there is a chance that the same object was encoded pre copy up and then we need to stay consistent with the same encoding also after copy up. In case a non-pure upper is not indexed, then it was copied up before NFS export support was enabled. In that case, we don't need to worry about staying consistent with pre copy up encoding and we encode an upper file handle. This mitigates the problem that with no index, we cannot find an upper inode from origin inode, so we cannot decode a non-indexed upper from origin file handle. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24ovl: decode connected upper dir file handlesAmir Goldstein
Until this change, we decoded upper file handles by instantiating an overlay dentry from the real upper dentry. This is sufficient to handle pure upper files, but insufficient to handle merge/impure dirs. To that end, if decoded real upper dir is connected and hashed, we lookup an overlay dentry with the same path as the real upper dir. If decoded real upper is non-dir, we instantiate a disconnected overlay dentry as before this change. Because ovl_fh_to_dentry() returns a connected overlay dir dentry, exportfs never needs to call get_parent() and get_name() to reconnect an upper overlay dir. Because connectable non-dir file handles are not supported, exportfs will not be able to use fh_to_parent() and get_name() methods to reconnect a disconnected non-dir to its parent. Therefore, the methods get_parent() and get_name() are implemented just to print out a sanity warning and the method fh_to_parent() is implemented to warn the user that using the 'subtree_check' exportfs option is not supported. An alternative approach could have been to implement instantiating of an overlay directory inode from origin/index and implement get_parent() and get_name() by calling into underlying fs operations and them instantiating the overlay parent dir. The reasons for not choosing the get_parent() approach were: - Obtaining a disconnected overlay dir dentry would requires a delicate re-factoring of ovl_lookup() to get a dentry with overlay parent info. It was preferred to avoid doing that re-factoring unless it was proven worthy. - Going down the path of disconnected dir would mean that the (non trivial) code path of d_splice_alias() could be traveled and that meant writing more tests and introduces race cases that are very hard to hit on purpose. Taking the path of connecting overlay dentry by forward lookup is therefore the safe and boring way to avoid surprises. The culprits of the chosen "connected overlay dentry" approach: - We need to take special care to rename of ancestors while connecting the overlay dentry by real dentry path. These subtleties are usually handled by generic exportfs and VFS code. - In a hypothetical workload, we could end up in a loop trying to connect, interrupted by rename and restarting connect forever. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>