| Message ID | 20210118193516.2915706-11-hch@lst.de (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
| Series | [01/11] xfs: factor out a xfs_ilock_iocb helper | expand |
On Mon, Jan 18, 2021 at 08:35:15PM +0100, Christoph Hellwig wrote: > Add a flag to signal an I/O that is not file system block aligned. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap/direct-io.c | 7 +++++++ > include/linux/iomap.h | 8 ++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 32dbbf7dd4aadb..d93019ee4c9e3e 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -485,6 +485,13 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > iomap_flags |= IOMAP_NOWAIT; > } > > + if (dio_flags & IOMAP_DIO_UNALIGNED) { > + ret = -EAGAIN; > + if (pos >= dio->i_size) > + goto out_free_dio; This also needs to check for pos+len > dio->i_size on a write as iomap_dio_rw_actor will do unconditional sub-block zeroing in that case, too. > + iomap_flags |= IOMAP_UNALIGNED; > + } > + > ret = filemap_write_and_wait_range(mapping, pos, end); > if (ret) > goto out_free_dio; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index b322598dc10ec0..2fa94ec9583d0a 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -122,6 +122,7 @@ struct iomap_page_ops { > #define IOMAP_FAULT (1 << 3) /* mapping for page fault */ > #define IOMAP_DIRECT (1 << 4) /* direct I/O */ > #define IOMAP_NOWAIT (1 << 5) /* do not block */ > +#define IOMAP_UNALIGNED (1 << 6) /* do not allocate blocks */ > > struct iomap_ops { > /* > @@ -262,6 +263,13 @@ struct iomap_dio_ops { > */ > #define IOMAP_DIO_FORCE_WAIT (1 << 0) > > +/* > + * Direct I/O that is not aligned to the file system block. Do not allocate > + * blocks and do not zero partial blocks, fall back to the caller by returning > + * -EAGAIN instead. > + */ > +#define IOMAP_DIO_UNALIGNED (1 << 1) I'd describe it a little bit differently, clearly indicating that this is for optional behaviour and not needed on all unaligned DIO. /* * Filesystems may need to special case DIO that is not aligned to * block boundaries. If they set IOMAP_DIO_UNALIGNED on an unaligned * IO, then do not allocate blocks or zero partial blocks, but * instead fall back to the caller by returning -EAGAIN so they can * handle these conditions correctly. */ Cheers, Dave.
On Mon, Jan 18, 2021 at 08:35:15PM +0100, Christoph Hellwig wrote: > Add a flag to signal an I/O that is not file system block aligned. > + if (dio_flags & IOMAP_DIO_UNALIGNED) { There are a number of things that DIO has to be aligned to -- memory addresses, for example. Can we be a little more verbose about what is unaligned here? eg if (dio_flags & IOMAP_DIO_FS_UNALIGNED) (or FSBLK_UNALIGNED, or ... something).
I've renamed it to IOMAP_DIO_SUBBLOCK
On Mon, Jan 18, 2021 at 08:35:15PM +0100, Christoph Hellwig wrote: > Add a flag to signal an I/O that is not file system block aligned. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap/direct-io.c | 7 +++++++ > include/linux/iomap.h | 8 ++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 32dbbf7dd4aadb..d93019ee4c9e3e 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -485,6 +485,13 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > iomap_flags |= IOMAP_NOWAIT; > } > > + if (dio_flags & IOMAP_DIO_UNALIGNED) { > + ret = -EAGAIN; > + if (pos >= dio->i_size) > + goto out_free_dio; > + iomap_flags |= IOMAP_UNALIGNED; > + } > + > ret = filemap_write_and_wait_range(mapping, pos, end); > if (ret) > goto out_free_dio; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index b322598dc10ec0..2fa94ec9583d0a 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -122,6 +122,7 @@ struct iomap_page_ops { > #define IOMAP_FAULT (1 << 3) /* mapping for page fault */ > #define IOMAP_DIRECT (1 << 4) /* direct I/O */ > #define IOMAP_NOWAIT (1 << 5) /* do not block */ > +#define IOMAP_UNALIGNED (1 << 6) /* do not allocate blocks */ > > struct iomap_ops { > /* > @@ -262,6 +263,13 @@ struct iomap_dio_ops { > */ > #define IOMAP_DIO_FORCE_WAIT (1 << 0) > > +/* > + * Direct I/O that is not aligned to the file system block. Do not allocate > + * blocks and do not zero partial blocks, fall back to the caller by returning > + * -EAGAIN instead. > + */ > +#define IOMAP_DIO_UNALIGNED (1 << 1) The code changes look fine, but as for the name, I found it a little confusing even after changing it to IOMAP_DIO_SUBBLOCK. See my reply to patch 11 for more details. --D > + > ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > const struct iomap_ops *ops, const struct iomap_dio_ops *dops, > unsigned int flags); > -- > 2.29.2 >
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 32dbbf7dd4aadb..d93019ee4c9e3e 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -485,6 +485,13 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, iomap_flags |= IOMAP_NOWAIT; } + if (dio_flags & IOMAP_DIO_UNALIGNED) { + ret = -EAGAIN; + if (pos >= dio->i_size) + goto out_free_dio; + iomap_flags |= IOMAP_UNALIGNED; + } + ret = filemap_write_and_wait_range(mapping, pos, end); if (ret) goto out_free_dio; diff --git a/include/linux/iomap.h b/include/linux/iomap.h index b322598dc10ec0..2fa94ec9583d0a 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -122,6 +122,7 @@ struct iomap_page_ops { #define IOMAP_FAULT (1 << 3) /* mapping for page fault */ #define IOMAP_DIRECT (1 << 4) /* direct I/O */ #define IOMAP_NOWAIT (1 << 5) /* do not block */ +#define IOMAP_UNALIGNED (1 << 6) /* do not allocate blocks */ struct iomap_ops { /* @@ -262,6 +263,13 @@ struct iomap_dio_ops { */ #define IOMAP_DIO_FORCE_WAIT (1 << 0) +/* + * Direct I/O that is not aligned to the file system block. Do not allocate + * blocks and do not zero partial blocks, fall back to the caller by returning + * -EAGAIN instead. + */ +#define IOMAP_DIO_UNALIGNED (1 << 1) + ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, const struct iomap_dio_ops *dops, unsigned int flags);
Add a flag to signal an I/O that is not file system block aligned. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap/direct-io.c | 7 +++++++ include/linux/iomap.h | 8 ++++++++ 2 files changed, 15 insertions(+)