knfsd: nfsd: Handle ERESTARTSYS from syscalls.
knfsd: nfsd: Handle ERESTARTSYS from syscalls.

OCFS2 can return -ERESTARTSYS from write requests (and possibly
elsewhere) if there is a signal pending.

If nfsd is shutdown (by sending a signal to each thread) while there
is still an IO load from the client, each thread could handle one last
request with a signal pending.  This can result in -ERESTARTSYS
which is not understood by nfserrno() and so is reflected back to
the client as nfserr_io aka -EIO.  This is wrong.

Instead, interpret ERESTARTSYS to mean "try again later" by returning
nfserr_jukebox.  The client will resend and - if the server is
restarted - the write will (hopefully) be successful and everyone will
be happy.

 The symptom that I narrowed down to this was:
    copy a large file via NFS to an OCFS2 filesystem, and restart
    the nfs server during the copy.
    The 'cp' might get an -EIO, and the file will be corrupted -
    presumably holes in the middle where writes appeared to fail.

Signed-off-by: Neil Brown <1c00aa603bb92d594c03cff60ecf8e63b2a5bcb1@suse.de>
Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@citi.umich.edu>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas