linux.git/include/linux/iomap.h, branch v5.7-rc2

iomap: use a srcmap for a read-modify-write I/O

2019-10-21T15:51:59+00:00

The srcmap is used to identify where the read is to be performed from.
It is passed to ->iomap_begin, which can fill it in if we need to read
data for partially written blocks from a different location than the
write target.  The srcmap is only supported for buffered writes so far.

Signed-off-by: Goldwyn Rodrigues 
[hch: merged two patches, removed the IOMAP_F_COW flag, use iomap as
      srcmap if not set, adjust length down to srcmap end as well]
Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Acked-by: Goldwyn Rodrigues

iomap: renumber IOMAP_HOLE to 0

2019-10-21T15:51:59+00:00

Instead of keeping a separate unnamed state for uninitialized iomaps,
renumber IOMAP_HOLE to zero so that an uninitialized iomap is treated
as a hole.

Suggested-by: Darrick J. Wong 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: ignore non-shared or non-data blocks in xfs_file_dirty

2019-10-21T15:51:59+00:00

xfs_file_dirty is used to unshare reflink blocks.  Rename the function
to xfs_file_unshare to better document that purpose, and skip iomaps
that are not shared and don't need zeroing.  This will allow to simplify
the caller.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: better document the IOMAP_F_* flags

2019-10-21T15:51:59+00:00

The documentation for IOMAP_F_* is a bit disorganized, and doesn't
mention the fact that most flags are set by the file system and consumed
by the iomap core, while IOMAP_F_SIZE_CHANGED is set by the core and
consumed by the file system.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Allison Collins 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: move struct iomap_page out of iomap.h

2019-10-21T15:51:59+00:00

Now that all the writepage code is in the iomap code there is no
need to keep this structure public.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Dave Chinner 
Reviewed-by: Carlos Maiolino 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: lift the xfs writeback code to iomap

2019-10-21T15:51:59+00:00

Take the xfs writeback code and move it to fs/iomap.  A new structure
with three methods is added as the abstraction from the generic writeback
code to the file system.  These methods are used to map blocks, submit an
ioend, and cancel a page that encountered an error before it was added to
an ioend.

Signed-off-by: Christoph Hellwig 
[darrick: rename ->submit_ioend to ->prepare_ioend to clarify what it
does]
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner

iomap: iomap that extends beyond EOF should be marked dirty

2019-10-17T20:12:01+00:00

When doing a direct IO that spans the current EOF, and there are
written blocks beyond EOF that extend beyond the current write, the
only metadata update that needs to be done is a file size extension.

However, we don't mark such iomaps as IOMAP_F_DIRTY to indicate that
there is IO completion metadata updates required, and hence we may
fail to correctly sync file size extensions made in IO completion
when O_DSYNC writes are being used and the hardware supports FUA.

Hence when setting IOMAP_F_DIRTY, we need to also take into account
whether the iomap spans the current EOF. If it does, then we need to
mark it dirty so that IO completion will call generic_write_sync()
to flush the inode size update to stable storage correctly.

Fixes: 3460cac1ca76 ("iomap: Use FUA for pure data O_DSYNC DIO writes")
Signed-off-by: Dave Chinner 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
[darrick: removed the ext4 part; they'll handle it separately]
Signed-off-by: Darrick J. Wong

iomap: Allow forcing of waiting for running DIO in iomap_dio_rw()

2019-10-15T15:43:42+00:00

Filesystems do not support doing IO as asynchronous in some cases. For
example in case of unaligned writes or in case file size needs to be
extended (e.g. for ext4). Instead of forcing filesystem to wait for AIO
in such cases, add argument to iomap_dio_rw() which makes the function
wait for IO completion. This also results in executing
iomap_dio_complete() inline in iomap_dio_rw() providing its return value
to the caller as for ordinary sync IO.

Signed-off-by: Jan Kara 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: move the iomap_dio_rw ->end_io callback into a structure

2019-09-19T22:32:45+00:00

Add a new iomap_dio_ops structure that for now just contains the end_io
handler.  This avoid storing the function pointer in a mutable structure,
which is a possible exploit vector for kernel code execution, and prepares
for adding a submit_io handler that btrfs needs.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong

iomap: split size and error for iomap_dio_rw ->end_io

2019-09-19T22:32:44+00:00

Modify the calling convention for the iomap_dio_rw ->end_io() callback.
Rather than passing either dio->error or dio->size as the 'size' argument,
instead pass both the dio->error and the dio->size value separately.

In the instance that an error occurred during a write, we currently cannot
determine whether any blocks have been allocated beyond the current EOF and
data has subsequently been written to these blocks within the ->end_io()
callback. As a result, we cannot judge whether we should take the truncate
failed write path. Having both dio->error and dio->size will allow us to
perform such checks within this callback.

Signed-off-by: Matthew Bobrowski 
[hch: minor cleanups]
Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Darrick J. Wong 
Reviewed-by: Matthew Wilcox (Oracle)