On 2021/9/16 8:30, Darrick J. Wong wrote:
On Wed, Sep 15, 2021 at 06:45:01PM +0800, Shiyang Ruan wrote:Introduce xfs_mmaplock_two_inodes_and_break_dax_layout() for dax files who are going to be deduped. After that, call compare range function only when files are both DAX or not. Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com> Reviewed-by: Darrick J. Wong <djw...@kernel.org> Reviewed-by: Christoph Hellwig <h...@lst.de> --- fs/xfs/xfs_file.c | 2 +- fs/xfs/xfs_inode.c | 80 +++++++++++++++++++++++++++++++++++++++++--- fs/xfs/xfs_inode.h | 1 + fs/xfs/xfs_reflink.c | 4 +-- 4 files changed, 80 insertions(+), 7 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 2ef1930374d2..c3061723613c 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -846,7 +846,7 @@ xfs_wait_dax_page( xfs_ilock(ip, XFS_MMAPLOCK_EXCL); }-static int+int xfs_break_dax_layouts( struct inode *inode, bool *retry) diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index a4f6f034fb81..bdc084cdbf46 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -3790,6 +3790,61 @@ xfs_iolock_two_inodes_and_break_layout( return 0; }+static int+xfs_mmaplock_two_inodes_and_break_dax_layout( + struct xfs_inode *ip1, + struct xfs_inode *ip2) +{ + int error, attempts = 0; + bool retry; + struct page *page; + struct xfs_log_item *lp; + + if (ip1->i_ino > ip2->i_ino) + swap(ip1, ip2); + +again: + retry = false; + /* Lock the first inode */ + xfs_ilock(ip1, XFS_MMAPLOCK_EXCL); + error = xfs_break_dax_layouts(VFS_I(ip1), &retry); + if (error || retry) { + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + if (error == 0 && retry) + goto again; + return error; + } + + if (ip1 == ip2) + return 0; + + /* Nested lock the second inode */ + lp = &ip1->i_itemp->ili_item; + if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) { + if (!xfs_ilock_nowait(ip2, + xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1))) { + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + if ((++attempts % 5) == 0) + delay(1); /* Don't just spin the CPU */ + goto again; + }I suspect we don't need this part for grabbing the MMAPLOCK^W pagecache invalidatelock. The AIL only grabs the ILOCK, never the IOLOCK or the MMAPLOCK.
Maybe I have misunderstood this part.What I want is to lock the two inode nestedly. This code is copied from xfs_lock_two_inodes(), which checks this AIL during locking two inode with each of the three kinds of locks.
But I also found the recent merged function: filemap_invalidate_lock_two() just locks two inode directly without checking AIL. So, I am not if the AIL check is needed in this case.
+ } else + xfs_ilock(ip2, xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1)); + /* + * We cannot use xfs_break_dax_layouts() directly here because it may + * need to unlock & lock the XFS_MMAPLOCK_EXCL which is not suitable + * for this nested lock case. + */ + page = dax_layout_busy_page(VFS_I(ip2)->i_mapping); + if (page && page_ref_count(page) != 1) {Do you think the patch "ext4/xfs: add page refcount helper" would be a good cleanup to head this series? https://lore.kernel.org/linux-xfs/20210913161604.31981-1-alex.sie...@amd.com/T/#m59cf7cd5c0d521ad487fa3a15d31c3865db88bdf
Got it. -- Thanks, Ruan
The rest of the logic looks ok. --D+ xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL); + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + goto again; + } + + return 0; +} + /* * Lock two inodes so that userspace cannot initiate I/O via file syscalls or * mmap activity. @@ -3804,8 +3859,19 @@ xfs_ilock2_io_mmap( ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2)); if (ret) return ret; - filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping, - VFS_I(ip2)->i_mapping); + + if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) { + ret = xfs_mmaplock_two_inodes_and_break_dax_layout(ip1, ip2); + if (ret) { + inode_unlock(VFS_I(ip2)); + if (ip1 != ip2) + inode_unlock(VFS_I(ip1)); + return ret; + } + } else + filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping, + VFS_I(ip2)->i_mapping); + return 0; }@@ -3815,8 +3881,14 @@ xfs_iunlock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2) { - filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping, - VFS_I(ip2)->i_mapping); + if (IS_DAX(VFS_I(ip1)) && IS_DAX(VFS_I(ip2))) { + xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL); + if (ip1 != ip2) + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + } else + filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping, + VFS_I(ip2)->i_mapping); + inode_unlock(VFS_I(ip2)); if (ip1 != ip2) inode_unlock(VFS_I(ip1)); diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index b21b177832d1..f7e26fe31a26 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -472,6 +472,7 @@ enum xfs_prealloc_flags {int xfs_update_prealloc_flags(struct xfs_inode *ip,enum xfs_prealloc_flags flags); +int xfs_break_dax_layouts(struct inode *inode, bool *retry); int xfs_break_layouts(struct inode *inode, uint *iolock, enum layout_break_reason reason);diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.cindex 9d876e268734..3b99c9dfcf0d 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1327,8 +1327,8 @@ xfs_reflink_remap_prep( if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest)) goto out_unlock;- /* Don't share DAX file data for now. */- if (IS_DAX(inode_in) || IS_DAX(inode_out)) + /* Don't share DAX file data with non-DAX file. */ + if (IS_DAX(inode_in) != IS_DAX(inode_out)) goto out_unlock;if (!IS_DAX(inode_in))-- 2.33.0
