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  1. 12 Apr, 2018 16 commits
    • Amir Goldstein's avatar
      ovl: consistent i_ino for non-samefs with xino · 12574a9f
      Amir Goldstein authored 
      When overlay layers are not all on the same fs, but all inode numbers
of underlying fs do not use the high 'xino' bits, overlay st_ino values
are constant and persistent.

In that case, set i_ino value to the same value as st_ino for nfsd
readdirplus validator.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      12574a9f
    • Amir Goldstein's avatar
      ovl: constant st_ino for non-samefs with xino · e487d889
      Amir Goldstein authored 
      On 64bit systems, when overlay layers are not all on the same fs, but
all inode numbers of underlying fs are not using the high bits, use the
high bits to partition the overlay st_ino address space.  The high bits
hold the fsid (upper fsid is 0).  This way overlay inode numbers are unique
and all inodes use overlay st_dev.  Inode numbers are also persistent
for a given layer configuration.

Currently, our only indication for available high ino bits is from a
filesystem that supports file handles and uses the default encode_fh()
operation, which encodes a 32bit inode number.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      e487d889
    • Amir Goldstein's avatar
      ovl: allocate anon bdev per unique lower fs · 5148626b
      Amir Goldstein authored 
      Instead of allocating an anonymous bdev per lower layer, allocate
one anonymous bdev per every unique lower fs that is different than
upper fs.

Every unique lower fs is assigned an fsid > 0 and the number of
unique lower fs are stored in ofs->numlowerfs.

The assigned fsid is stored in the lower layer struct and will be
used also for inode number multiplexing.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      5148626b
    • Amir Goldstein's avatar
      ovl: factor out ovl_map_dev_ino() helper · da309e8c
      Amir Goldstein authored 
      A helper for ovl_getattr() to map the values of st_dev and st_ino
according to constant st_ino rules.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      da309e8c
    • Miklos Szeredi's avatar
      ovl: cleanup ovl_update_time() · 8f35cf51
      Miklos Szeredi authored 
      No need to mess with an alias, the upperdentry can be retrieved directly
from the overlay inode.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      8f35cf51
    • Miklos Szeredi's avatar
      ovl: add WARN_ON() for non-dir redirect cases · 3a291774
      Miklos Szeredi authored 
      Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      3a291774
    • Vivek Goyal's avatar
      ovl: cleanup setting OVL_INDEX · 0471a9cd
      Vivek Goyal authored 
      Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      0471a9cd
    • Vivek Goyal's avatar
      ovl: set d->is_dir and d->opaque for last path element · 102b0d11
      Vivek Goyal authored 
      Certain properties in ovl_lookup_data should be set only for the last
element of the path. IOW, if we are calling ovl_lookup_single() for an
absolute redirect, then d->is_dir and d->opaque do not make much sense
for intermediate path elements. Instead set them only if dentry being
lookup is last path element.

As of now we do not seem to be making use of d->opaque if it is set for
a path/dentry in lower. But just define the semantics so that future code
can make use of this assumption.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      102b0d11
    • Vivek Goyal's avatar
      ovl: Do not check for redirect if this is last layer · e9b77f90
      Vivek Goyal authored 
      If we are looking in last layer, then there should not be any need to
process redirect. redirect information is used only for lookup in next
lower layer and there is no more lower layer to look into. So no need
to process redirects.

IOW, ignore redirects on lowest layer.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      e9b77f90
    • Amir Goldstein's avatar
      ovl: lookup in inode cache first when decoding lower file handle · 8b58924a
      Amir Goldstein authored 
      When decoding a lower file handle, we need to check if lower file was
copied up and indexed and if it has a whiteout index, we need to check
if this is an unlinked but open non-dir before returning -ESTALE.

To find out if this is an unlinked but open non-dir we need to lookup
an overlay inode in inode cache by lower inode and that requires decoding
the lower file handle before looking in inode cache.

Before this change, if the lower inode turned out to be a directory, we
may have paid an expensive cost to reconnect that lower directory for
nothing.

After this change, we start by decoding a disconnected lower dentry and
using the lower inode for looking up an overlay inode in inode cache.
If we find overlay inode and dentry in cache, we avoid the index lookup
overhead. If we don't find an overlay inode and dentry in cache, then we
only need to decode a connected lower dentry in case the lower dentry is
a non-indexed directory.

The xfstests group overlay/exportfs tests decoding overlayfs file
handles after drop_caches with different states of the file at encode
and decode time. Overall the tests in the group call ovl_lower_fh_to_d()
89 times to decode a lower file handle.

Before this change, the tests called ovl_get_index_fh() 75 times and
reconnect_one() 61 times.
After this change, the tests call ovl_get_index_fh() 70 times and
reconnect_one() 59 times. The 2 cases where reconnect_one() was avoided
are cases where a non-upper directory file handle was encoded, then the
directory removed and then file handle was decoded.

To demonstrate the affect on decoding file handles with hot inode/dentry
cache, the drop_caches call in the tests was disabled. Without
drop_caches, there are no reconnect_one() calls at all before or after
the change. Before the change, there are 75 calls to ovl_get_index_fh(),
exactly as the case with drop_caches. After the change, there are only
10 calls to ovl_get_index_fh().
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      8b58924a
    • Amir Goldstein's avatar
      ovl: do not try to reconnect a disconnected origin dentry · 8a22efa1
      Amir Goldstein authored 
      On lookup of non directory, we try to decode the origin file handle
stored in upper inode. The origin file handle is supposed to be decoded
to a disconnected non-dir dentry, which is fine, because we only need
the lower inode of a copy up origin.

However, if the origin file handle somehow turns out to be a directory
we pay the expensive cost of reconnecting the directory dentry, only to
get a mismatch file type and drop the dentry.

Optimize this case by explicitly opting out of reconnecting the dentry.
Opting-out of reconnect is done by passing a NULL acceptable callback
to exportfs_decode_fh().

While the case described above is a strange corner case that does not
really need to be optimized, the API added for this optimization will
be used by a following patch to optimize a more common case of decoding
an overlayfs file handle.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      8a22efa1
    • Amir Goldstein's avatar
      ovl: disambiguate ovl_encode_fh() · 5b2cccd3
      Amir Goldstein authored 
      Rename ovl_encode_fh() to ovl_encode_real_fh() to differentiate from the
exportfs function ovl_encode_inode_fh() and change the latter to
ovl_encode_fh() to match the exportfs method name.

Rename ovl_decode_fh() to ovl_decode_real_fh() for consistency.
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      5b2cccd3
    • Amir Goldstein's avatar
      ovl: set lower layer st_dev only if setting lower st_ino · 9f99e50d
      Amir Goldstein authored 
      For broken hardlinks, we do not return lower st_ino, so we should
also not return lower pseudo st_dev.

Fixes: a0c5ad30 ("ovl: relax same fs constraint for constant st_ino")
Cc: <stable@vger.kernel.org> #v4.15
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      9f99e50d
    • Amir Goldstein's avatar
      ovl: fix lookup with middle layer opaque dir and absolute path redirects · 3ec9b3fa
      Amir Goldstein authored 
      As of now if we encounter an opaque dir while looking for a dentry, we set
d->last=true. This means that there is no need to look further in any of
the lower layers. This works fine as long as there are no redirets or
relative redircts. But what if there is an absolute redirect on the
children dentry of opaque directory. We still need to continue to look into
next lower layer. This patch fixes it.

Here is an example to demonstrate the issue. Say you have following setup.

upper:  /redirect (redirect=/a/b/c)
lower1: /a/[b]/c       ([b] is opaque) (c has absolute redirect=/a/b/d/)
lower0: /a/b/d/foo

Now "redirect" dir should merge with lower1:/a/b/c/ and lower0:/a/b/d.
Note, despite the fact lower1:/a/[b] is opaque, we need to continue to look
into lower0 because children c has an absolute redirect.

Following is a reproducer.

Watch me make foo disappear:

 $ mkdir lower middle upper work work2 merged
 $ mkdir lower/origin
 $ touch lower/origin/foo
 $ mount -t overlay none merged/ \
         -olowerdir=lower,upperdir=middle,workdir=work2
 $ mkdir merged/pure
 $ mv merged/origin merged/pure/redirect
 $ umount merged
 $ mount -t overlay none merged/ \
         -olowerdir=middle:lower,upperdir=upper,workdir=work
 $ mv merged/pure/redirect merged/redirect

Now you see foo inside a twice redirected merged dir:

 $ ls merged/redirect
 foo
 $ umount merged
 $ mount -t overlay none merged/ \
         -olowerdir=middle:lower,upperdir=upper,workdir=work

After mount cycle you don't see foo inside the same dir:

 $ ls merged/redirect

During middle layer lookup, the opaqueness of middle/pure is left in
the lookup state and then middle/pure/redirect is wrongly treated as
opaque.

Fixes: 02b69b28 ("ovl: lookup redirects")
Cc: <stable@vger.kernel.org> #v4.10
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      3ec9b3fa
    • Vivek Goyal's avatar
      ovl: Set d->last properly during lookup · 452061fd
      Vivek Goyal authored 
      d->last signifies that this is the last layer we are looking into and there
is no more. And that means this allows for some optimzation opportunities
during lookup. For example, in ovl_lookup_single() we don't have to check
for opaque xattr of a directory is this is the last layer we are looking
into (d->last = true).

But knowing for sure whether we are looking into last layer can be very
tricky. If redirects are not enabled, then we can look at poe->numlower and
figure out if the lookup we are about to is last layer or not. But if
redircts are enabled then it is possible poe->numlower suggests that we are
looking in last layer, but there is an absolute redirect present in found
element and that redirects us to a layer in root and that means lookup will
continue in lower layers further.

For example, consider following.

/upperdir/pure (opaque=y)
/upperdir/pure/foo (opaque=y,redirect=/bar)
/lowerdir/bar

In this case pure is "pure upper". When we look for "foo", that time
poe->numlower=0. But that alone does not mean that we will not search for a
merge candidate in /lowerdir. Absolute redirect changes that.

IOW, d->last should not be set just based on poe->numlower if redirects are
enabled. That can lead to setting d->last while it should not have and that
means we will not check for opaque xattr while we should have.

So do this.

 - If redirects are not enabled, then continue to rely on poe->numlower
   information to determine if it is last layer or not.

 - If redirects are enabled, then set d->last = true only if this is the
   last layer in root ovl_entry (roe).
Suggested-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Fixes: 02b69b28 ("ovl: lookup redirects")
Cc: <stable@vger.kernel.org> #v4.10
      452061fd
    • Amir Goldstein's avatar
      ovl: set i_ino to the value of st_ino for NFS export · 695b46e7
      Amir Goldstein authored 
      Eddie Horng reported that readdir of an overlayfs directory that
was exported via NFSv3 returns entries with d_type set to DT_UNKNOWN.
The reason is that while preparing the response for readdirplus, nfsd
checks inside encode_entryplus_baggage() that a child dentry's inode
number matches the value of d_ino returns by overlayfs readdir iterator.

Because the overlayfs inodes use arbitrary inode numbers that are not
correlated with the values of st_ino/d_ino, NFSv3 falls back to not
encoding d_type. Although this is an allowed behavior, we can fix it for
the case of all overlayfs layers on the same underlying filesystem.

When NFS export is enabled and d_ino is consistent with st_ino
(samefs), set the same value also to i_ino in ovl_fill_inode() for all
overlayfs inodes, nfsd readdirplus sanity checks will pass.
ovl_fill_inode() may be called from ovl_new_inode(), before real inode
was created with ino arg 0. In that case, i_ino will be updated to real
upper inode i_ino on ovl_inode_init() or ovl_inode_update().
Reported-by: default avatarEddie Horng <eddiehorng.tw@gmail.com>
Tested-by: default avatarEddie Horng <eddiehorng.tw@gmail.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Fixes: 8383f174 ("ovl: wire up NFS export operations")
Cc: <stable@vger.kernel.org> #v4.16
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      695b46e7
  3. 25 Mar, 2018 10 commits
  5. 24 Mar, 2018 1 commit
  7. 23 Mar, 2018 13 commits
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