puffs_suspend(3) - NetBSD Manual Pages

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PUFFS_SUSPEND(3)        NetBSD Library Functions Manual       PUFFS_SUSPEND(3)


NAME

     puffs_suspend -- puffs file system suspension and snapshotting


LIBRARY

     puffs Convenience Library (libpuffs, -lpuffs)


SYNOPSIS

     #include <puffs.h>

     int
     puffs_fs_suspend(struct puffs_usermount *pu);


DESCRIPTION

     The function puffs_fs_suspend() requests the kernel to suspend operations
     to the file system indicated by pu.  There are several possible outcomes:
     nothing, an error or success.  These will be indicated through the call-
     back of the same name.  The file system must set this callback if it
     wants to be notified of file system suspension.  The interface call
     itself returns 0 on success or -1 on error and sets errno.  In case an
     error is returned, the callback will never be called.  However, the con-
     verse does not hold and the callback may never be called even if the
     library call is successful.

     In case the kernel is successful to start suspending the file system, the
     callback is called with status PUFFS_SUSPEND START.  The file system
     implementation may use this as a hint on how to handle following opera-
     tions.  Once the file system has successfully been suspended, the status
     PUFFS_SUSPEND_SUSPENDED will be delivered.  In case there was an error
     while suspending, PUFFS_SUSPEND_ERROR is given.  This effectively nulli-
     fies any PUFFS_SUSPEND_START given earlier.  Operation will automatically
     resume after suspension and the status PUFFS_SUSPEND_RESUME is delivered
     to the callback.  Error or success is always provided in case start is
     given.

     The file system is supposed to do a file system specific snapshotting
     routine when it receives PUFFS_SUSPEND_SUSPENDED.


SEE ALSO

     puffs(3), puffs_cc(3)


BUGS

     Currently the implementation works only for single-threaded file systems
     which do not use puffs_cc.

     File system data and metadata are not always totally correctly synchro-
     nized at suspend.

NetBSD 5.1                     January 27, 2007                     NetBSD 5.1