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xfs: allow xfs_lock_two_inodes to take different EXCL/SHARED modes

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Refactor xfs_lock_two_inodes to take separate locking modes for each
inode.  Specifically, this enables us to take a SHARED lock on one inode
and an EXCL lock on the other.  The lock class (MMAPLOCK/ILOCK) must be
the same for each inode.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong
2018-01-26 15:27:33 -08:00
parent 1364b1d4b5
commit 7c2d238ac6
4 changed files with 39 additions and 22 deletions
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49
fs/xfs/xfs_inode.c
View File

@@ -546,23 +546,36 @@ again:
/*
* xfs_lock_two_inodes() can only be used to lock one type of lock at a time -
* the iolock, the mmaplock or the ilock, but not more than one at a time. If we
* lock more than one at a time, lockdep will report false positives saying we
* have violated locking orders.
* the mmaplock or the ilock, but not more than one type at a time. If we lock
* more than one at a time, lockdep will report false positives saying we have
* violated locking orders. The iolock must be double-locked separately since
* we use i_rwsem for that. We now support taking one lock EXCL and the other
* SHARED.
*/
void
xfs_lock_two_inodes(
xfs_inode_t *ip0,
xfs_inode_t *ip1,
uint lock_mode)
struct xfs_inode *ip0,
uint ip0_mode,
struct xfs_inode *ip1,
uint ip1_mode)
{
xfs_inode_t *temp;
struct xfs_inode *temp;
uint mode_temp;
int attempts = 0;
xfs_log_item_t *lp;
ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL))
ASSERT(!(lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
ASSERT(hweight32(ip0_mode) == 1);
ASSERT(hweight32(ip1_mode) == 1);
ASSERT(!(ip0_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
ASSERT(!(ip1_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
!(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
!(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
!(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
!(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
ASSERT(ip0->i_ino != ip1->i_ino);
@@ -570,10 +583,13 @@ xfs_lock_two_inodes(
temp = ip0;
ip0 = ip1;
ip1 = temp;
mode_temp = ip0_mode;
ip0_mode = ip1_mode;
ip1_mode = mode_temp;
}
again:
xfs_ilock(ip0, xfs_lock_inumorder(lock_mode, 0));
xfs_ilock(ip0, xfs_lock_inumorder(ip0_mode, 0));
/*
* If the first lock we have locked is in the AIL, we must TRY to get
@@ -582,18 +598,17 @@ xfs_lock_two_inodes(
*/
lp = (xfs_log_item_t *)ip0->i_itemp;
if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(lock_mode, 1))) {
xfs_iunlock(ip0, lock_mode);
if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(ip1_mode, 1))) {
xfs_iunlock(ip0, ip0_mode);
if ((++attempts % 5) == 0)
delay(1); /* Don't just spin the CPU */
goto again;
}
} else {
xfs_ilock(ip1, xfs_lock_inumorder(lock_mode, 1));
xfs_ilock(ip1, xfs_lock_inumorder(ip1_mode, 1));
}
}
void
__xfs_iflock(
struct xfs_inode *ip)
@@ -1421,7 +1436,7 @@ xfs_link(
if (error)
goto std_return;
xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);
xfs_lock_two_inodes(sip, XFS_ILOCK_EXCL, tdp, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
@@ -2585,7 +2600,7 @@ xfs_remove(
goto std_return;
}
xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);
xfs_lock_two_inodes(dp, XFS_ILOCK_EXCL, ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);