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2018-07-20ovl: Modify ovl_lookup() and friends to lookup metacopy dentryVivek Goyal5-18/+131
This patch modifies ovl_lookup() and friends to lookup metacopy dentries. It also allows for presence of metacopy dentries in lower layer. During lookup, check for presence of OVL_XATTR_METACOPY and if not present, set OVL_UPPERDATA bit in flags. We don't support metacopy feature with nfs_export. So in nfs_export code, we set OVL_UPPERDATA flag set unconditionally if upper inode exists. Do not follow metacopy origin if we find a metacopy only inode and metacopy feature is not enabled for that mount. Like redirect, this can have security implications where an attacker could hand craft upper and try to gain access to file on lower which it should not have to begin with. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Use out_err instead of out_nomemVivek Goyal1-7/+10
Right now we use goto out_nomem which assumes error code is -ENOMEM. But there are other errors returned like -ESTALE as well. So instead of out_nomem, use out_err which will do ERR_PTR(err). That way one can put error code in err and jump to out_err. This just code reorganization and no change of functionality. I am about to add more code and this organization helps laying more code and error paths on top of it. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: A new xattr OVL_XATTR_METACOPY for file on upperVivek Goyal4-11/+142
Now we will have the capability to have upper inodes which might be only metadata copy up and data is still on lower inode. So add a new xattr OVL_XATTR_METACOPY to distinguish between two cases. Presence of OVL_XATTR_METACOPY reflects that file has been copied up metadata only and and data will be copied up later from lower origin. So this xattr is set when a metadata copy takes place and cleared when data copy takes place. We also use a bit in ovl_inode->flags to cache OVL_UPPERDATA which reflects whether ovl inode has data or not (as opposed to metadata only copy up). If a file is copied up metadata only and later when same file is opened for WRITE, then data copy up takes place. We copy up data, remove METACOPY xattr and then set the UPPERDATA flag in ovl_inode->flags. While all these operations happen with oi->lock held, read side of oi->flags can be lockless. That is another thread on another cpu can check if UPPERDATA flag is set or not. So this gives us an ordering requirement w.r.t UPPERDATA flag. That is, if another cpu sees UPPERDATA flag set, then it should be guaranteed that effects of data copy up and remove xattr operations are also visible. For example. CPU1 CPU2 ovl_open() acquire(oi->lock) ovl_open_maybe_copy_up() ovl_copy_up_data() open_open_need_copy_up() vfs_removexattr() ovl_already_copied_up() ovl_dentry_needs_data_copy_up() ovl_set_flag(OVL_UPPERDATA) ovl_test_flag(OVL_UPPERDATA) release(oi->lock) Say CPU2 is copying up data and in the end sets UPPERDATA flag. But if CPU1 perceives the effects of setting UPPERDATA flag but not the effects of preceding operations (ex. upper that is not fully copied up), it will be a problem. Hence this patch introduces smp_wmb() on setting UPPERDATA flag operation and smp_rmb() on UPPERDATA flag test operation. May be some other lock or barrier is already covering it. But I am not sure what that is and is it obvious enough that we will not break it in future. So hence trying to be safe here and introducing barriers explicitly for UPPERDATA flag/bit. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Add helper ovl_already_copied_up()Vivek Goyal3-19/+28
There are couple of places where we need to know if file is already copied up (in lockless manner). Right now its open coded and there are only two conditions to check. Soon this patch series will introduce another condition to check and Amir wants to introduce one more. So introduce a helper instead to check this so that code is easier to read. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Copy up only metadata during copy up where it makes senseVivek Goyal1-1/+24
If it makes sense to copy up only metadata during copy up, do it. This is done for regular files which are not opened for WRITE. Right now ->metacopy is set to 0 always. Last patch in the series will remove the hard coded statement and enable metacopy feature. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: During copy up, first copy up metadata and then dataVivek Goyal1-19/+17
Just a little re-ordering of code. This helps with next patch where after copying up metadata, we skip data copying step, if needed. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Provide a mount option metacopy=on/off for metadata copyupVivek Goyal4-4/+92
By default metadata only copy up is disabled. Provide a mount option so that users can choose one way or other. Also provide a kernel config and module option to enable/disable metacopy feature. metacopy feature requires redirect_dir=on when upper is present. Otherwise, it requires redirect_dir=follow atleast. As of now, metacopy does not work with nfs_export=on. So if both metacopy=on and nfs_export=on then nfs_export is disabled. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Move the copy up helpers to copy_up.cVivek Goyal3-33/+33
Right now two copy up helpers are in inode.c. Amir suggested it might be better to move these to copy_up.c. There will one more related function which will come in later patch. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: Initialize ovl_inode->redirect in ovl_get_inode()Vivek Goyal3-7/+5
ovl_inode->redirect is an inode property and should be initialized in ovl_get_inode() only when we are adding a new inode to cache. If inode is already in cache, it is already initialized and we should not be touching ovl_inode->redirect field. As of now this is not a problem as redirects are used only for directories which don't share inode. But soon I want to use redirects for regular files also and there it can become an issue. Hence, move ->redirect initialization in ovl_get_inode(). Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-20ovl: fix documentation of non-standard behaviorMiklos Szeredi1-21/+30
We can now drop description of the ro/rw inconsistency from the documentation. Also clarify, that now fully standard compliant behavior can be enabled with kernel/module/mount options. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: obsolete "check_copy_up" module optionMiklos Szeredi1-23/+7
This was provided for debugging the ro/rw inconsistecy. The inconsitency is now gone so this option is obsolete. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: remove open_flags from d_real()Miklos Szeredi5-55/+13
Opening regular files on overlayfs is now handled via ovl_open(). Remove the now unused "open_flags" argument from d_op->d_real() and the d_real() helper. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "fsnotify: support overlayfs"Miklos Szeredi1-9/+5
This reverts commit f3fbbb079263bd29ae592478de6808db7e708267. Overlayfs now works correctly without adding hacks to fsnotify. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Partially revert "locks: fix file locking on overlayfs"Miklos Szeredi3-24/+8
This partially reverts commit c568d68341be7030f5647def68851e469b21ca11. Overlayfs files will now automatically get the correct locks, no need to hack overlay support in VFS. It is a partial revert, because it leaves the locks_inode() calls in place and defines locks_inode() to file_inode(). We could revert those as well, but it would be unnecessary code churn and it makes sense to document that we are getting the inode for locking purposes. Don't revert MS_NOREMOTELOCK yet since that has been part of the userspace API for some time (though not in a useful way). Will try to remove internal flags later when the dust around the new mount API settles. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Acked-by: Jeff Layton <jlayton@kernel.org>
2018-07-18Revert "vfs: do get_write_access() on upper layer of overlayfs"Miklos Szeredi2-15/+3
This reverts commit 4d0c5ba2ff79ef9f5188998b29fd28fcb05f3667. We now get write access on both overlay and underlying layers so this patch is no longer needed for correct operation. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "vfs: add flags to d_real()"Miklos Szeredi6-12/+11
This reverts commit 495e642939114478a5237a7d91661ba93b76f15a. No user of "flags" argument of d_real() remain. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "vfs: update ovl inode before relatime check"Miklos Szeredi4-35/+8
This reverts commit 598e3c8f72f5b77c84d2cb26cfd936ffb3cfdbaa. Overlayfs no longer relies on the vfs correct atime handling. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "ovl: fix relatime for directories"Miklos Szeredi3-23/+4
This reverts commit cd91304e7190b4c4802f8e413ab2214b233e0260. Overlayfs no longer relies on the vfs correct atime handling. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: fix freeze protection in mnt_want_write_file() for overlayfsMiklos Szeredi1-3/+4
The underlying real file used by overlayfs still contains the overlay path. This results in mnt_want_write_file() calls by the filesystem getting freeze protection on the wrong inode (the overlayfs one instead of the real one). Fix by using file_inode(file)->i_sb instead of file->f_path.mnt->mnt_sb. Reported-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
2018-07-18Revert "ovl: don't allow writing ioctl on lower layer"Miklos Szeredi4-70/+9
This reverts commit 7c6893e3c9abf6a9676e060a1e35e5caca673d57. Overlayfs no longer relies on the vfs for checking writability of files. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "ovl: fix may_write_real() for overlayfs directories"Miklos Szeredi1-3/+1
This reverts commit 954c736f865d6c0c68ae4263a2f3502ee7c447a3. Overlayfs no longer relies on the vfs for checking writability of files. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: don't open realMiklos Szeredi1-6/+1
Let overlayfs do its thing when opening a file. This enables stacking and fixes the corner case when a file is opened for read, modified through a writable open, and data is read from the read-only file. After this patch the read-only open will not return stale data even in this case. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-18ovl: add reflink/copyfile/dedup supportMiklos Szeredi1-0/+87
Since set of arguments are so similar, handle in a common helper. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add O_DIRECT supportMiklos Szeredi1-0/+3
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_fiemap()Miklos Szeredi1-1/+28
Implement stacked fiemap(). Need to split inode operations for regular file (which has fiemap) and special file (which doesn't have fiemap). Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add lsattr/chattr supportMiklos Szeredi1-0/+79
Implement FS_IOC_GETFLAGS and FS_IOC_SETFLAGS. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_fallocate()Miklos Szeredi1-0/+24
Implement stacked fallocate. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_mmap()Miklos Szeredi1-0/+32
Implement stacked mmap. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_fsync()Miklos Szeredi1-0/+23
Implement stacked fsync(). Don't sync if lower (noticed by Amir Goldstein). Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_write_iter()Miklos Szeredi1-0/+39
Implement stacked writes. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add ovl_read_iter()Miklos Szeredi1-0/+67
Implement stacked reading. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: add helper to return real fileMiklos Szeredi1-0/+60
In the common case we can just use the real file cached in file->private_data. There are two exceptions: 1) File has been copied up since open: in this unlikely corner case just use a throwaway real file for the operation. If ever this becomes a perfomance problem (very unlikely, since overlayfs has been doing most fine without correctly handling this case at all), then we can deal with that by updating the cached real file. 2) File's f_flags have changed since open: no need to reopen the cached real file, we can just change the flags there as well. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: stack file opsMiklos Szeredi4-2/+82
Implement file operations on a regular overlay file. The underlying file is opened separately and cached in ->private_data. It might be worth making an exception for such files when accounting in nr_file to confirm to userspace expectations. We are only adding a small overhead (248bytes for the struct file) since the real inode and dentry are pinned by overlayfs anyway. This patch doesn't have any effect, since the vfs will use d_real() to find the real underlying file to open. The patch at the end of the series will actually enable this functionality. AV: make it use open_with_fake_path(), don't mess with override_creds SzM: still need to mess with override_creds() until no fs uses current_cred() in their open method. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-18ovl: deal with overlay files in ovl_d_real()Miklos Szeredi1-0/+4
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: copy up file size as wellMiklos Szeredi2-9/+2
Copy i_size of the underlying inode to the overlay inode in ovl_copyattr(). This is in preparation for stacking I/O operations on overlay files. This patch shouldn't have any observable effect. Remove stale comment from ovl_setattr() [spotted by Vivek Goyal]. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Revert "Revert "ovl: get_write_access() in truncate""Miklos Szeredi1-0/+21
This reverts commit 31c3a7069593b072bd57192b63b62f9a7e994e9a. Re-add functionality dealing with i_writecount on truncate to overlayfs. This patch shouldn't have any observable effects, since we just re-assert the writecout that vfs_truncate() already got for us. This is in preparation for moving overlay functionality out of the VFS. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: copy up inode flagsMiklos Szeredi2-0/+8
On inode creation copy certain inode flags from the underlying real inode to the overlay inode. This is in preparation for moving overlay functionality out of the VFS. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18ovl: copy up timesMiklos Szeredi4-9/+37
Copy up mtime and ctime to overlay inode after times in real object are modified. Be careful not to dirty cachelines when not necessary. This is in preparation for moving overlay functionality out of the VFS. This patch shouldn't have any observable effect. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: export vfs_dedupe_file_range_one() to modulesMiklos Szeredi2-3/+7
This is needed by the stacked dedupe implementation in overlayfs. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: export vfs_ioctl() to modulesMiklos Szeredi3-1/+3
This is needed by the stacked ioctl implementation in overlayfs. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18vfs: make open_with_fake_path() not contribute to nr_filesMiklos Szeredi4-22/+53
Stacking file operations in overlay will store an extra open file for each overlay file opened. The overhead is just that of "struct file" which is about 256bytes, because overlay already pins an extra dentry and inode when the file is open, which add up to a much larger overhead. For fear of breaking working setups, don't start accounting the extra file. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-18Merge branch 'dedupe-cleanup' into overlayfs-nextMiklos Szeredi6-84/+74
Following series for stacking overlay files depends on this mini series.
2018-07-18Merge branch 'for-ovl' of ↵Miklos Szeredi26-183/+137
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs into overlayfs-next This gives us the open_with_fake_path() helper that is needed for stacked open files in overlay and mmap in particular.
2018-07-17ovl: fix wrong use of impure dir cache in ovl_iterate()Amir Goldstein1-2/+17
Only upper dir can be impure, but if we are in the middle of iterating a lower real dir, dir could be copied up and marked impure. We only want the impure cache if we started iterating a real upper dir to begin with. Aditya Kali reported that the following reproducer hits the WARN_ON(!cache->refcount) in ovl_get_cache(): docker run --rm drupal:8.5.4-fpm-alpine \ sh -c 'cd /var/www/html/vendor/symfony && \ chown -R www-data:www-data . && ls -l .' Reported-by: Aditya Kali <adityakali@google.com> Tested-by: Aditya Kali <adityakali@google.com> Fixes: 4edb83bb1041 ('ovl: constant d_ino for non-merge dirs') Cc: <stable@vger.kernel.org> # v4.14 Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-07-12new helper: open_with_fake_path()Al Viro2-0/+20
open a file by given inode, faking ->f_path. Use with shitloads of caution - at the very least you'd damn better make sure that some dentry alias of that inode is pinned down by the path in question. Again, this is no general-purpose interface and I hope it will eventually go away. Right now overlayfs wants something like that, but nothing else should. Any out-of-tree code with bright idea of using this one *will* eventually get hurt, with zero notice and great delight on my part. I refuse to use EXPORT_SYMBOL_GPL(), especially in situations when it's really EXPORT_SYMBOL_DONT_USE_IT(), but don't take that export as "you are welcome to use it". Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-12now we can fold open_check_o_direct() into do_dentry_open()Al Viro3-19/+6
These checks are better off in do_dentry_open(); the reason we couldn't put them there used to be that callers couldn't tell what kind of cleanup would do_dentry_open() failure call for. Now that we have FMODE_OPENED, cleanup is the same in all cases - it's simply fput(). So let's fold that into do_dentry_open(), as Christoph's patch tried to. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-12lift fput() on late failures into path_openat()Al Viro1-16/+12
Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-12fold put_filp() into fput()Al Viro4-21/+10
Just check FMODE_OPENED in __fput() and be done with that... Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-12introduce FMODE_OPENEDAl Viro3-1/+5
basically, "is that instance set up enough for regular fput(), or do we want put_filp() for that one". NOTE: the only alloc_file() caller that could be followed by put_filp() is in arch/ia64/kernel/perfmon.c, which is (Kconfig-level) broken. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-07-12->file_open(): lose cred argumentAl Viro6-10/+10
Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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