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authorSteve French <stfrench@microsoft.com>2020-04-09 21:42:18 -0500
committerSteve French <stfrench@microsoft.com>2020-04-10 13:32:32 -0500
commit4e8aea30f7751ce7c4b158aa0c04e7744d281cc3 (patch)
tree97609c93ac38f8b665e4996a457d82108cb5a4b1 /fs/cifs/inode.c
parent1dc94b7381bd5f71aa417487abaf3bd3d70938c4 (diff)
downloadlinux-4e8aea30f7751ce7c4b158aa0c04e7744d281cc3.tar.bz2
smb3: enable swap on SMB3 mounts
Add experimental support for allowing a swap file to be on an SMB3 mount. There are use cases where swapping over a secure network filesystem is preferable. In some cases there are no local block devices large enough, and network block devices can be hard to setup and secure. And in some cases there are no local block devices at all (e.g. with the recent addition of remote boot over SMB3 mounts). There are various enhancements that can be added later e.g.: - doing a mandatory byte range lock over the swapfile (until the Linux VFS is modified to notify the file system that an open is for a swapfile, when the file can be opened "DENY_ALL" to prevent others from opening it). - pinning more buffers in the underlying transport to minimize memory allocations in the TCP stack under the fs - documenting how to create ACLs (on the server) to secure the swapfile (or adding additional tools to cifs-utils to make it easier) Signed-off-by: Steve French <stfrench@microsoft.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Diffstat (limited to 'fs/cifs/inode.c')
-rw-r--r--fs/cifs/inode.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 8d01ec2dca66..8fbbdcdad8ff 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2026,6 +2026,10 @@ cifs_revalidate_mapping(struct inode *inode)
int rc;
unsigned long *flags = &CIFS_I(inode)->flags;
+ /* swapfiles are not supposed to be shared */
+ if (IS_SWAPFILE(inode))
+ return 0;
+
rc = wait_on_bit_lock_action(flags, CIFS_INO_LOCK, cifs_wait_bit_killable,
TASK_KILLABLE);
if (rc)