Re: [PATCH v5 7/7] fs/xfs: Add dax dedupe support
From: "Darrick J. Wong" <djwong@kernel.org>
Date: 2021-05-12 01:04:35
Also in:
linux-fsdevel, lkml
On Tue, May 11, 2021 at 11:09:33AM +0800, Shiyang Ruan wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- fs/xfs/xfs_file.c | 2 +- fs/xfs/xfs_inode.c | 66 +++++++++++++++++++++++++++++++++++++++++++- fs/xfs/xfs_inode.h | 1 + fs/xfs/xfs_reflink.c | 4 +-- 4 files changed, 69 insertions(+), 4 deletions(-)diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 38d8eca05aee..bd5002d38df4 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c@@ -823,7 +823,7 @@ 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 0369eb22c1bb..0774b6e2b940 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c@@ -3711,6 +3711,64 @@ xfs_iolock_two_inodes_and_break_layout( return 0; } +static int +xfs_mmaplock_two_inodes_and_break_dax_layout( + struct inode *src, + struct inode *dest)
MMAPLOCK is an xfs_inode lock, so please pass those in here.
+{
+ int error, attempts = 0;
+ bool retry;
+ struct xfs_inode *ip0, *ip1;
+ struct page *page;
+ struct xfs_log_item *lp;
+
+ if (src > dest)
+ swap(src, dest);The MMAPLOCK (and ILOCK) locking order is increasing inode number, not the address of the incore object. This is different (and not consistent with) i_rwsem/XFS_IOLOCK, but those are the rules.
+ ip0 = XFS_I(src);
+ ip1 = XFS_I(dest);
+
+again:
+ retry = false;
+ /* Lock the first inode */
+ xfs_ilock(ip0, XFS_MMAPLOCK_EXCL);
+ error = xfs_break_dax_layouts(src, &retry);
+ if (error || retry) {
+ xfs_iunlock(ip0, XFS_MMAPLOCK_EXCL);
+ goto again;
+ }
+
+ if (src == dest)
+ return 0;
+
+ /* Nested lock the second inode */
+ lp = &ip0->i_itemp->ili_item;
+ if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
+ if (!xfs_ilock_nowait(ip1,
+ xfs_lock_inumorder(XFS_MMAPLOCK_EXCL, 1))) {
+ xfs_iunlock(ip0, XFS_MMAPLOCK_EXCL);
+ if ((++attempts % 5) == 0)
+ delay(1); /* Don't just spin the CPU */
+ goto again;
+ }
+ } else
+ xfs_ilock(ip1, 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(dest->i_mapping);
+ if (page) {
+ if (page_ref_count(page) != 1) {
This could be flattened to:
if (page && page_ref_count(page) != 1) {
...
}
--D
quoted hunk ↗ jump to hunk
+ xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + xfs_iunlock(ip0, XFS_MMAPLOCK_EXCL); + goto again; + } + } + + return 0; +} + /* * Lock two inodes so that userspace cannot initiate I/O via file syscalls or * mmap activity.@@ -3721,10 +3779,16 @@ xfs_ilock2_io_mmap( struct xfs_inode *ip2) { int ret; + struct inode *ino1 = VFS_I(ip1); + struct inode *ino2 = VFS_I(ip2); - ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2)); + ret = xfs_iolock_two_inodes_and_break_layout(ino1, ino2); if (ret) return ret; + + if (IS_DAX(ino1) && IS_DAX(ino2)) + return xfs_mmaplock_two_inodes_and_break_dax_layout(ino1, ino2); + if (ip1 == ip2) xfs_ilock(ip1, XFS_MMAPLOCK_EXCL); elsediff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index ca826cfba91c..2d0b344fb100 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h@@ -457,6 +457,7 @@ 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.c index 9a780948dbd0..ff308304c5cd 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c@@ -1324,8 +1324,8 @@ 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))-- 2.31.1