NAME

       nbdkit-ext2-filter - read and write files inside ext2, ext3 or ext4 filesystems

SYNOPSIS

        nbdkit --filter=ext2 file fs.img ext2file=/disks/disk.raw

        nbdkit --filter=ext2 --filter=partition file fs.img \
           partition=1 ext2file=exportname

DESCRIPTION

       "nbdkit-ext2-filter" is an nbdkit filter which can read and write files inside ext2, ext3
       or ext4 filesystem images.

       Suppose you have an ext2/3/4 filesystem image called fs.img which contains inside itself a
       file called disk.raw inside a directory on the filesystem called /disks, then you could
       serve that file over NBD using:

        nbdkit --filter=ext2 file fs.img ext2file=/disks/disk.raw

       Commonly disk images are partitioned.  In that case, you must select just the partition of
       a disk image that contains an ext2 filesystem, by using nbdkit-partition-filter(1):

        nbdkit --filter=ext2 --filter=partition file fs.img \
           partition=1 ext2file=/disks/disk.raw

       This filter can both read and write to the file inside the filesystem.  Use the -r flag to
       force a readonly connection, but note this does not guarantee that no writes are made to
       the filesystem.  In particular we may have to replay the ext3 journal in order to open a
       filesystem even read-only.

       The filter does not support multiple parallel connections, because there is a risk of
       corrupting the filesystem (as if the filesystem was mounted by multiple machines).  If a
       second connection is made to nbdkit, it will block until the first connection closes.

       The filter is implemented using the ext2fs library which is provided in most Linux
       distros, and also available as part of the e2fsprogs project.

       nbdkit-guestfs-plugin(1) is a more generic plugin which can read files from all kinds of
       different filesystem types, even if they are partitioned or use logical volumes.  It uses
       libguestfs instead of e2fsprogs.

PARAMETERS

       ext2file=PATH
           The full path of the file within the filesystem that will be exposed over NBD.  The
           path must be absolute (starts with "/").

       ext2file=exportname
           The plugin will expose the path within the filesystem chosen by the exportname passed
           by the client.  Note that this mode allows the client to deduce which files exist
           within the disk image, which may be a security risk in some situations.

           At present, when using this mode, the server does not advertise any particular
           exports; however, you may use nbdkit-exportname-filter(1) to perform that task.
           Similarly, the underlying plugin must support the default export name, "".

FILES

       $filterdir/nbdkit-ext2-filter.so
           The filter.

           Use "nbdkit --dump-config" to find the location of $filterdir.

VERSION

       "nbdkit-ext2-filter" first appeared in nbdkit 1.18, replacing "nbdkit-ext2-plugin" which
       was added in nbdkit 1.4 and removed in nbdkit 1.22.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3), nbdkit-exportname-filter(1), nbdkit-partition-filter(1),
       nbdkit-guestfs-plugin(1), http://e2fsprogs.sourceforge.net/, fuse2fs(1).

AUTHORS

       Eric Blake

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2018-2020 Red Hat Inc.

LICENSE

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