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* vfs: make first argument of dir_context.actor typedMiklos Szeredi2014-10-311-3/+5
| | | | | Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* ovl: initialize ->is_cursorMiklos Szeredi2014-10-311-0/+1
| | | | | Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: fix lockdep misannotationMiklos Szeredi2014-10-281-1/+1
| | | | | | | | | | | | | | | | In an overlay directory that shadows an empty lower directory, say /mnt/a/empty102, do: touch /mnt/a/empty102/x unlink /mnt/a/empty102/x rmdir /mnt/a/empty102 It's actually harmless, but needs another level of nesting between I_MUTEX_CHILD and I_MUTEX_NORMAL. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Tested-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* ovl: fix check for cursorMiklos Szeredi2014-10-281-5/+6
| | | | | | | | | | | | | ovl_cache_entry.name is now an array not a pointer, so it makes no sense test for it being NULL. Detected by coverity. From: Miklos Szeredi <mszeredi@suse.cz> Fixes: 68bf8611076a ("overlayfs: make ovl_cache_entry->name an array instead of +pointer") Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: barriers for opening upper-layer directoryAl Viro2014-10-281-1/+2
| | | | | | | | | make sure that a) all stores done by opening struct file don't leak past storing the reference in od->upperfile b) the lockless side has read dependency barrier Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: embed middle into overlay_readdir_dataAl Viro2014-10-241-7/+5
| | | | | | same story... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: embed root into overlay_readdir_dataAl Viro2014-10-241-6/+5
| | | | | | | no sense having it a pointer - all instances have it pointing to local variable in the same stack frame Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: make ovl_cache_entry->name an array instead of pointerAl Viro2014-10-241-6/+5
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: don't hold ->i_mutex over opening the real directoryAl Viro2014-10-241-6/+13
| | | | | | just use it to serialize the assignment Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: limit filesystem stacking depthMiklos Szeredi2014-10-241-0/+9
| | | | | | | | | | | | | | Add a simple read-only counter to super_block that indicates how deep this is in the stack of filesystems. Previously ecryptfs was the only stackable filesystem and it explicitly disallowed multiple layers of itself. Overlayfs, however, can be stacked recursively and also may be stacked on top of ecryptfs or vice versa. To limit the kernel stack usage we must limit the depth of the filesystem stack. Initially the limit is set to 2. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* overlayfs: implement show_optionsErez Zadok2014-10-241-28/+48
| | | | | | | | | | | | This is useful because of the stacking nature of overlayfs. Users like to find out (via /proc/mounts) which lower/upper directory were used at mount time. AV: even failing ovl_parse_opt() could've done some kstrdup() AV: failure of ovl_alloc_entry() should end up with ENOMEM, not EINVAL Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* overlayfs: add statfs supportAndy Whitcroft2014-10-241-0/+40
| | | | | | | | | | | | | | Add support for statfs to the overlayfs filesystem. As the upper layer is the target of all write operations assume that the space in that filesystem is the space in the overlayfs. There will be some inaccuracy as overwriting a file will copy it up and consume space we were not expecting, but it is better than nothing. Use the upper layer dentry and mount from the overlayfs root inode, passing the statfs call to that filesystem. Signed-off-by: Andy Whitcroft <apw@canonical.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* overlay filesystemMiklos Szeredi2014-10-248-0/+3282
Overlayfs allows one, usually read-write, directory tree to be overlaid onto another, read-only directory tree. All modifications go to the upper, writable layer. This type of mechanism is most often used for live CDs but there's a wide variety of other uses. The implementation differs from other "union filesystem" implementations in that after a file is opened all operations go directly to the underlying, lower or upper, filesystems. This simplifies the implementation and allows native performance in these cases. The dentry tree is duplicated from the underlying filesystems, this enables fast cached lookups without adding special support into the VFS. This uses slightly more memory than union mounts, but dentries are relatively small. Currently inodes are duplicated as well, but it is a possible optimization to share inodes for non-directories. Opening non directories results in the open forwarded to the underlying filesystem. This makes the behavior very similar to union mounts (with the same limitations vs. fchmod/fchown on O_RDONLY file descriptors). Usage: mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper/upper,workdir=/upper/work /overlay The following cotributions have been folded into this patch: Neil Brown <neilb@suse.de>: - minimal remount support - use correct seek function for directories - initialise is_real before use - rename ovl_fill_cache to ovl_dir_read Felix Fietkau <nbd@openwrt.org>: - fix a deadlock in ovl_dir_read_merged - fix a deadlock in ovl_remove_whiteouts Erez Zadok <ezk@fsl.cs.sunysb.edu> - fix cleanup after WARN_ON Sedat Dilek <sedat.dilek@googlemail.com> - fix up permission to confirm to new API Robin Dong <hao.bigrat@gmail.com> - fix possible leak in ovl_new_inode - create new inode in ovl_link Andy Whitcroft <apw@canonical.com> - switch to __inode_permission() - copy up i_uid/i_gid from the underlying inode AV: - ovl_copy_up_locked() - dput(ERR_PTR(...)) on two failure exits - ovl_clear_empty() - one failure exit forgetting to do unlock_rename(), lack of check for udir being the parent of upper, dropping and regaining the lock on udir (which would require _another_ check for parent being right). - bogus d_drop() in copyup and rename [fix from your mail] - copyup/remove and copyup/rename races [fix from your mail] - ovl_dir_fsync() leaving ERR_PTR() in ->realfile - ovl_entry_free() is pointless - it's just a kfree_rcu() - fold ovl_do_lookup() into ovl_lookup() - manually assigning ->d_op is wrong. Just use ->s_d_op. [patches picked from Miklos]: * copyup/remove and copyup/rename races * bogus d_drop() in copyup and rename Also thanks to the following people for testing and reporting bugs: Jordi Pujol <jordipujolp@gmail.com> Andy Whitcroft <apw@canonical.com> Michal Suchanek <hramrach@centrum.cz> Felix Fietkau <nbd@openwrt.org> Erez Zadok <ezk@fsl.cs.sunysb.edu> Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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