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nfs/localio: Ensure DIO WRITE's IO on stable storage upon completion 

LOCALIO's misaligned DIO WRITE support requires synchronous IO for any
misaligned head and/or tail that are issued using buffered IO.  In
addition, it is important that the O_DIRECT middle be on stable
storage upon its completion via AIO.

Otherwise, a misaligned DIO WRITE could mix buffered IO for the
head/tail and direct IO for the DIO-aligned middle -- which could lead
to problems associated with deferred writes to stable storage (such as
out of order partial completions causing incorrect advancement of the
file's offset, etc).

Fixes: c817248fc8 ("nfs/localio: add proper O_DIRECT support for READ and WRITE")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
pull/1354/merge
Mike Snitzer 2025-10-27 13:52:28 -04:00 committed by Anna Schumaker
parent d0497dd274
commit d32ddfeb55
1 changed files with 5 additions and 1 deletions
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6
fs/nfs/localio.c
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@ -485,8 +485,12 @@ nfs_local_iters_init(struct nfs_local_kiocb *iocb, int rw)
struct nfs_local_dio local_dio;
if (nfs_is_local_dio_possible(iocb, rw, len, &local_dio) &&
nfs_local_iters_setup_dio(iocb, rw, v, len, &local_dio) != 0)
nfs_local_iters_setup_dio(iocb, rw, v, len, &local_dio) != 0) {
/* Ensure DIO WRITE's IO on stable storage upon completion */
if (rw == ITER_SOURCE)
iocb->kiocb.ki_flags |= IOCB_DSYNC|IOCB_SYNC;
return; /* is DIO-aligned */
}
}
/* Use buffered IO */