ovl: verify index dir matches upper dir

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An index dir contains persistent hardlinks to files in upper dir.
Therefore, we must never mount an existing index dir with a differnt
upper dir.

Store the upper root dir file handle in index dir inode when index
dir is created and verify the file handle before using an existing
index dir on mount.

Add an 'is_upper' flag to the overlay file handle encoding and set it
when encoding the upper root file handle. This is not critical for index
dir verification, but it is good practice towards a standard overlayfs
file handle format for NFS export.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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Amir Goldstein 2017-06-21 15:28:38 +03:00 • committed by Miklos Szeredi

parent 8b88a2e640

commit 54fb347e83

4 changed files with 27 additions and 8 deletions

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12

fs/overlayfs/copy_up.c

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4

fs/overlayfs/namei.c

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6

fs/overlayfs/overlayfs.h

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13

fs/overlayfs/super.c

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