| Message ID | 20240619115426.332708-2-hch@lst.de (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | [1/6] xfs: move the dio write relocking out of xfs_ilock_for_iomap | expand |
On Wed, Jun 19, 2024 at 01:53:51PM +0200, Christoph Hellwig wrote: > About half of xfs_ilock_for_iomap deals with a special case for direct > I/O writes to COW files that need to take the ilock exclusively. Move > this code into the one callers that cares and simplify > xfs_ilock_for_iomap. > > Signed-off-by: Christoph Hellwig <hch@lst.de> It took me a few minutes to sort this out, but yeah, directio writes are the only place where we do this shared->cow->excl promotion dance. Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/xfs/xfs_iomap.c | 71 ++++++++++++++++++++++------------------------ > 1 file changed, 34 insertions(+), 37 deletions(-) > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index 3783426739258c..b0085e5972393a 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -717,53 +717,30 @@ imap_needs_cow( > return true; > } > > +/* > + * Extents not yet cached requires exclusive access, don't block for > + * IOMAP_NOWAIT. > + * > + * This is basically an opencoded xfs_ilock_data_map_shared() call, but with > + * support for IOMAP_NOWAIT. > + */ > static int > xfs_ilock_for_iomap( > struct xfs_inode *ip, > unsigned flags, > unsigned *lockmode) > { > - unsigned int mode = *lockmode; > - bool is_write = flags & (IOMAP_WRITE | IOMAP_ZERO); > - > - /* > - * COW writes may allocate delalloc space or convert unwritten COW > - * extents, so we need to make sure to take the lock exclusively here. > - */ > - if (xfs_is_cow_inode(ip) && is_write) > - mode = XFS_ILOCK_EXCL; > - > - /* > - * Extents not yet cached requires exclusive access, don't block. This > - * is an opencoded xfs_ilock_data_map_shared() call but with > - * non-blocking behaviour. > - */ > - if (xfs_need_iread_extents(&ip->i_df)) { > - if (flags & IOMAP_NOWAIT) > - return -EAGAIN; > - mode = XFS_ILOCK_EXCL; > - } > - > -relock: > if (flags & IOMAP_NOWAIT) { > - if (!xfs_ilock_nowait(ip, mode)) > + if (xfs_need_iread_extents(&ip->i_df)) > + return -EAGAIN; > + if (!xfs_ilock_nowait(ip, *lockmode)) > return -EAGAIN; > } else { > - xfs_ilock(ip, mode); > + if (xfs_need_iread_extents(&ip->i_df)) > + *lockmode = XFS_ILOCK_EXCL; > + xfs_ilock(ip, *lockmode); > } > > - /* > - * The reflink iflag could have changed since the earlier unlocked > - * check, so if we got ILOCK_SHARED for a write and but we're now a > - * reflink inode we have to switch to ILOCK_EXCL and relock. > - */ > - if (mode == XFS_ILOCK_SHARED && is_write && xfs_is_cow_inode(ip)) { > - xfs_iunlock(ip, mode); > - mode = XFS_ILOCK_EXCL; > - goto relock; > - } > - > - *lockmode = mode; > return 0; > } > > @@ -801,7 +778,7 @@ xfs_direct_write_iomap_begin( > int nimaps = 1, error = 0; > bool shared = false; > u16 iomap_flags = 0; > - unsigned int lockmode = XFS_ILOCK_SHARED; > + unsigned int lockmode; > u64 seq; > > ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO)); > @@ -817,10 +794,30 @@ xfs_direct_write_iomap_begin( > if (offset + length > i_size_read(inode)) > iomap_flags |= IOMAP_F_DIRTY; > > + /* > + * COW writes may allocate delalloc space or convert unwritten COW > + * extents, so we need to make sure to take the lock exclusively here. > + */ > + if (xfs_is_cow_inode(ip)) > + lockmode = XFS_ILOCK_EXCL; > + else > + lockmode = XFS_ILOCK_SHARED; > + > +relock: > error = xfs_ilock_for_iomap(ip, flags, &lockmode); > if (error) > return error; > > + /* > + * The reflink iflag could have changed since the earlier unlocked > + * check, check if it again and relock if needed. > + */ > + if (xfs_is_cow_inode(ip) && lockmode == XFS_ILOCK_SHARED) { > + xfs_iunlock(ip, lockmode); > + lockmode = XFS_ILOCK_EXCL; > + goto relock; > + } > + > error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap, > &nimaps, 0); > if (error) > -- > 2.43.0 > >
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 3783426739258c..b0085e5972393a 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -717,53 +717,30 @@ imap_needs_cow( return true; } +/* + * Extents not yet cached requires exclusive access, don't block for + * IOMAP_NOWAIT. + * + * This is basically an opencoded xfs_ilock_data_map_shared() call, but with + * support for IOMAP_NOWAIT. + */ static int xfs_ilock_for_iomap( struct xfs_inode *ip, unsigned flags, unsigned *lockmode) { - unsigned int mode = *lockmode; - bool is_write = flags & (IOMAP_WRITE | IOMAP_ZERO); - - /* - * COW writes may allocate delalloc space or convert unwritten COW - * extents, so we need to make sure to take the lock exclusively here. - */ - if (xfs_is_cow_inode(ip) && is_write) - mode = XFS_ILOCK_EXCL; - - /* - * Extents not yet cached requires exclusive access, don't block. This - * is an opencoded xfs_ilock_data_map_shared() call but with - * non-blocking behaviour. - */ - if (xfs_need_iread_extents(&ip->i_df)) { - if (flags & IOMAP_NOWAIT) - return -EAGAIN; - mode = XFS_ILOCK_EXCL; - } - -relock: if (flags & IOMAP_NOWAIT) { - if (!xfs_ilock_nowait(ip, mode)) + if (xfs_need_iread_extents(&ip->i_df)) + return -EAGAIN; + if (!xfs_ilock_nowait(ip, *lockmode)) return -EAGAIN; } else { - xfs_ilock(ip, mode); + if (xfs_need_iread_extents(&ip->i_df)) + *lockmode = XFS_ILOCK_EXCL; + xfs_ilock(ip, *lockmode); } - /* - * The reflink iflag could have changed since the earlier unlocked - * check, so if we got ILOCK_SHARED for a write and but we're now a - * reflink inode we have to switch to ILOCK_EXCL and relock. - */ - if (mode == XFS_ILOCK_SHARED && is_write && xfs_is_cow_inode(ip)) { - xfs_iunlock(ip, mode); - mode = XFS_ILOCK_EXCL; - goto relock; - } - - *lockmode = mode; return 0; } @@ -801,7 +778,7 @@ xfs_direct_write_iomap_begin( int nimaps = 1, error = 0; bool shared = false; u16 iomap_flags = 0; - unsigned int lockmode = XFS_ILOCK_SHARED; + unsigned int lockmode; u64 seq; ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO)); @@ -817,10 +794,30 @@ xfs_direct_write_iomap_begin( if (offset + length > i_size_read(inode)) iomap_flags |= IOMAP_F_DIRTY; + /* + * COW writes may allocate delalloc space or convert unwritten COW + * extents, so we need to make sure to take the lock exclusively here. + */ + if (xfs_is_cow_inode(ip)) + lockmode = XFS_ILOCK_EXCL; + else + lockmode = XFS_ILOCK_SHARED; + +relock: error = xfs_ilock_for_iomap(ip, flags, &lockmode); if (error) return error; + /* + * The reflink iflag could have changed since the earlier unlocked + * check, check if it again and relock if needed. + */ + if (xfs_is_cow_inode(ip) && lockmode == XFS_ILOCK_SHARED) { + xfs_iunlock(ip, lockmode); + lockmode = XFS_ILOCK_EXCL; + goto relock; + } + error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap, &nimaps, 0); if (error)
About half of xfs_ilock_for_iomap deals with a special case for direct I/O writes to COW files that need to take the ilock exclusively. Move this code into the one callers that cares and simplify xfs_ilock_for_iomap. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/xfs/xfs_iomap.c | 71 ++++++++++++++++++++++------------------------ 1 file changed, 34 insertions(+), 37 deletions(-)