seaweedfs/weed/mount/weedfs_file_io.go

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package mount
import (
"github.com/hanwen/go-fuse/v2/fuse"
)
/**
* Open a file
*
* Open flags are available in fi->flags. The following rules
* apply.
*
* - Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be
* filtered out / handled by the kernel.
*
* - Access modes (O_RDONLY, O_WRONLY, O_RDWR) should be used
* by the filesystem to check if the operation is
* permitted. If the ``-o default_permissions`` mount
* option is given, this check is already done by the
* kernel before calling open() and may thus be omitted by
* the filesystem.
*
* - When writeback caching is enabled, the kernel may send
* read requests even for files opened with O_WRONLY. The
* filesystem should be prepared to handle this.
*
* - When writeback caching is disabled, the filesystem is
* expected to properly handle the O_APPEND flag and ensure
* that each write is appending to the end of the file.
*
* - When writeback caching is enabled, the kernel will
* handle O_APPEND. However, unless all changes to the file
* come through the kernel this will not work reliably. The
* filesystem should thus either ignore the O_APPEND flag
* (and let the kernel handle it), or return an error
* (indicating that reliably O_APPEND is not available).
*
* Filesystem may store an arbitrary file handle (pointer,
* index, etc) in fi->fh, and use this in other all other file
* operations (read, write, flush, release, fsync).
*
* Filesystem may also implement stateless file I/O and not store
* anything in fi->fh.
*
* There are also some flags (direct_io, keep_cache) which the
* filesystem may set in fi, to change the way the file is opened.
* See fuse_file_info structure in <fuse_common.h> for more details.
*
* If this request is answered with an error code of ENOSYS
* and FUSE_CAP_NO_OPEN_SUPPORT is set in
* `fuse_conn_info.capable`, this is treated as success and
* future calls to open and release will also succeed without being
* sent to the filesystem process.
*
* Valid replies:
* fuse_reply_open
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
func (wfs *WFS) Open(cancel <-chan struct{}, in *fuse.OpenIn, out *fuse.OpenOut) (status fuse.Status) {
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var fileHandle *FileHandle
fileHandle, status = wfs.AcquireHandle(in.NodeId, in.Uid, in.Gid)
if status == fuse.OK {
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out.Fh = uint64(fileHandle.fh)
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// TODO https://github.com/libfuse/libfuse/blob/master/include/fuse_common.h#L64
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}
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return status
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}
/**
* Release an open file
*
* Release is called when there are no more references to an open
* file: all file descriptors are closed and all memory mappings
* are unmapped.
*
* For every open call there will be exactly one release call (unless
* the filesystem is force-unmounted).
*
* The filesystem may reply with an error, but error values are
* not returned to close() or munmap() which triggered the
* release.
*
* fi->fh will contain the value set by the open method, or will
* be undefined if the open method didn't set any value.
* fi->flags will contain the same flags as for open.
*
* Valid replies:
* fuse_reply_err
*
* @param req request handle
* @param ino the inode number
* @param fi file information
*/
func (wfs *WFS) Release(cancel <-chan struct{}, in *fuse.ReleaseIn) {
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wfs.ReleaseHandle(FileHandleId(in.Fh))
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}