mirror of
https://github.com/seaweedfs/seaweedfs.git
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72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
package mount
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import (
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"context"
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"io"
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"github.com/hanwen/go-fuse/v2/fuse"
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"github.com/seaweedfs/seaweedfs/weed/glog"
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)
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/**
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* Read data
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*
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* Read should send exactly the number of bytes requested except
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* on EOF or error, otherwise the rest of the data will be
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* substituted with zeroes. An exception to this is when the file
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* has been opened in 'direct_io' mode, in which case the return
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* value of the read system call will reflect the return value of
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* this operation.
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*
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* fi->fh will contain the value set by the open method, or will
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* be undefined if the open method didn't set any value.
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*
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* Valid replies:
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* fuse_reply_buf
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* fuse_reply_iov
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* fuse_reply_data
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* fuse_reply_err
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*
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* @param req request handle
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* @param ino the inode number
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* @param size number of bytes to read
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* @param off offset to read from
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* @param fi file information
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*/
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func (wfs *WFS) Read(cancel <-chan struct{}, in *fuse.ReadIn, buff []byte) (fuse.ReadResult, fuse.Status) {
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fh := wfs.GetHandle(FileHandleId(in.Fh))
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if fh == nil {
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return nil, fuse.ENOENT
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}
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fh.orderedMutex.Acquire(context.Background(), 1)
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defer fh.orderedMutex.Release(1)
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offset := int64(in.Offset)
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totalRead, err := readDataByFileHandle(buff, fh, offset)
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if err != nil {
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glog.Warningf("file handle read %s %d: %v", fh.FullPath(), totalRead, err)
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return nil, fuse.EIO
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}
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return fuse.ReadResultData(buff[:totalRead]), fuse.OK
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}
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func readDataByFileHandle(buff []byte, fhIn *FileHandle, offset int64) (int64, error) {
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// read data from source file
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size := len(buff)
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fhIn.lockForRead(offset, size)
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defer fhIn.unlockForRead(offset, size)
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n, tsNs, err := fhIn.readFromChunks(buff, offset)
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if err == nil || err == io.EOF {
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maxStop := fhIn.readFromDirtyPages(buff, offset, tsNs)
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n = max(maxStop-offset, n)
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}
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if err == io.EOF {
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err = nil
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}
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return n, err
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}
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