В линуксе mount --bind /dev /mnt/dev ЕМНИП On Sat, Jun 30, 2018 at 1:46 PM, Slawa Olhovchenkov <s...@zxy.spb.ru> wrote:
> On Fri, Jun 29, 2018 at 05:59:00PM +0300, Gena Makhomed wrote: > > > > Т.е. директории должны быть как бы зеркалами друг друга. > > > > > > Это возможно сделать? > > > > Теоретически - наверное возможно, если написать свой модуль ядра, > > который будет реализовывать эту логику на уровне файловой системы. > > > > кажется в лялихе тоже такое было. > > MOUNT_UNIONFS(8) FreeBSD System Manager's Manual > MOUNT_UNIONFS(8) > > NAME > mount_unionfs — mount union file systems > > SYNOPSIS > mount_unionfs [-b] [-o options] directory uniondir > > DESCRIPTION > The mount_unionfs utility attaches directory above uniondir in such a > way > that the contents of both directory trees remain visible. By default, > directory becomes the upper layer and uniondir becomes the lower > layer. > > The options are as follows: > > -b Deprecated. Use -o below instead. > > -o Options are specified with the -o flag followed by an option. > The following options are available: > > below Inverts the default position, so that directory > becomes > the lower layer and uniondir becomes the upper layer. > However, uniondir remains the mount point. > > copymode = traditional | transparent | masquerade > Specifies the way to create a file or a directory in > the > upper layer automatically when needed. The > traditional > mode uses the same way as the old unionfs for backward > compatibility, and transparent duplicates the file and > directory mode bits and the ownership in the lower > layer > to the created file in the upper layer. For behavior > of > the masquerade mode, see MASQUERADE MODE below. > > whiteout = always | whenneeded > Specifies whether whiteouts should always be made in > the > upper layer when removing a file or directory or only > when it already exists in the lower layer. > > udir=mode > Specifies directory mode bits in octal for masquerade > mode. > > ufile=mode > Specifies file mode bits in octal for masquerade mode. > > gid=gid > Specifies group for masquerade mode. > > uid=uid > Specifies user for masquerade mode. > > To enforce file system security, the user mounting a file system must > be > superuser or else have write permission on the mounted-on directory. > In > addition, the vfs.usermount sysctl(8) variable must be set to 1 to > permit > file system mounting by ordinary users. However, note that > transparent > and masquerade modes require vfs.usermount to be set to 0 because this > functionality can only be used by superusers. > > Filenames are looked up in the upper layer and then in the lower > layer. > If a directory is found in the lower layer, and there is no entry in > the > upper layer, then a shadow directory will be created in the upper > layer. > The ownership and the mode bits are set depending on the copymode > option. > In traditional mode, it will be owned by the user who originally did > the > union mount, with mode 0777 (“rwxrwxrwx”) modified by the umask in > effect > at that time. > > If a file exists in the upper layer then there is no way to access a > file > with the same name in the lower layer. If necessary, a combination of > loopback and union mounts can be made which will still allow the lower > files to be accessed by a different pathname. > > Except in the case of a directory, access to an object is granted via > the > normal file system access checks. For directories, the current user > must > have access to both the upper and lower directories (should they both > exist). > > Requests to create or modify objects in uniondir are passed to the > upper > layer with the exception of a few special cases. An attempt to open > for > writing a file which exists in the lower layer causes a copy of the > entire file to be made to the upper layer, and then for the upper > layer > copy to be opened. Similarly, an attempt to truncate a lower layer > file > to zero length causes an empty file to be created in the upper layer. > Any other operation which would ultimately require modification to the > lower layer fails with EROFS. > > The union file system manipulates the namespace, rather than > individual > file systems. The union operation applies recursively down the > directory > tree now rooted at uniondir. Thus any file systems which are mounted > under uniondir will take part in the union operation. This differs > from > the union option to mount(8) which only applies the union operation to > the mount point itself, and then only for lookups. > > _______________________________________________ > nginx-ru mailing list > nginx-ru@nginx.org > http://mailman.nginx.org/mailman/listinfo/nginx-ru
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