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authorChristoph Hellwig <hch@lst.de>2009-08-31 21:51:52 -0300
committerFelix Blyakher <felixb@sgi.com>2009-09-01 12:46:16 -0500
commitaa72a5cf00001d0b952c7c755be404b9118ceb2e (patch)
tree2100d71c9d697f48f4c868b6631242c7292e5fd4 /fs/xfs/xfs_trans_inode.c
parent13e6d5cdde0e785aa943810f08b801cadd0935df (diff)
downloadop-kernel-dev-aa72a5cf00001d0b952c7c755be404b9118ceb2e.zip
op-kernel-dev-aa72a5cf00001d0b952c7c755be404b9118ceb2e.tar.gz
xfs: simplify xfs_trans_iget
xfs_trans_iget is a wrapper for xfs_iget that adds the inode to the transaction after it is read. Except when the inode already is in the inode cache, in which case it returns the existing locked inode with increment lock recursion counts. Now, no one in the tree every decrements these lock recursion counts, so any user of this gets a potential double unlock when both the original owner of the inode and the xfs_trans_iget caller unlock it. When looking back in a git bisect in the historic XFS tree there was only one place that decremented these counts, xfs_trans_iput. Introduced in commit ca25df7a840f426eb566d52667b6950b92bb84b5 by Adam Sweeney in 1993, and removed in commit 19f899a3ab155ff6a49c0c79b06f2f61059afaf3 by Steve Lord in 2003. And as long as it didn't slip through git bisects cracks never actually used in that time frame. A quick audit of the callers of xfs_trans_iget shows that no caller really relies on this behaviour fortunately - xfs_ialloc allows this inode from disk so it must not be there before, and all the RT allocator routines only every add each RT bitmap inode once. In addition to removing lots of code and reducing the size of the inode item this patch also avoids the double inode cache lookup in each create/mkdir/mknod transaction. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Alex Elder <aelder@sgi.com> Signed-off-by: Felix Blyakher <felixb@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_trans_inode.c')
-rw-r--r--fs/xfs/xfs_trans_inode.c86
1 files changed, 5 insertions, 81 deletions
diff --git a/fs/xfs/xfs_trans_inode.c b/fs/xfs/xfs_trans_inode.c
index 23d276a..785ff10 100644
--- a/fs/xfs/xfs_trans_inode.c
+++ b/fs/xfs/xfs_trans_inode.c
@@ -49,30 +49,7 @@ xfs_trans_inode_broot_debug(
/*
- * Get and lock the inode for the caller if it is not already
- * locked within the given transaction. If it is already locked
- * within the transaction, just increment its lock recursion count
- * and return a pointer to it.
- *
- * For an inode to be locked in a transaction, the inode lock, as
- * opposed to the io lock, must be taken exclusively. This ensures
- * that the inode can be involved in only 1 transaction at a time.
- * Lock recursion is handled on the io lock, but only for lock modes
- * of equal or lesser strength. That is, you can recur on the io lock
- * held EXCL with a SHARED request but not vice versa. Also, if
- * the inode is already a part of the transaction then you cannot
- * go from not holding the io lock to having it EXCL or SHARED.
- *
- * Use the inode cache routine xfs_inode_incore() to find the inode
- * if it is already owned by this transaction.
- *
- * If we don't already own the inode, use xfs_iget() to get it.
- * Since the inode log item structure is embedded in the incore
- * inode structure and is initialized when the inode is brought
- * into memory, there is nothing to do with it here.
- *
- * If the given transaction pointer is NULL, just call xfs_iget().
- * This simplifies code which must handle both cases.
+ * Get an inode and join it to the transaction.
*/
int
xfs_trans_iget(
@@ -84,62 +61,11 @@ xfs_trans_iget(
xfs_inode_t **ipp)
{
int error;
- xfs_inode_t *ip;
-
- /*
- * If the transaction pointer is NULL, just call the normal
- * xfs_iget().
- */
- if (tp == NULL)
- return xfs_iget(mp, NULL, ino, flags, lock_flags, ipp, 0);
-
- /*
- * If we find the inode in core with this transaction
- * pointer in its i_transp field, then we know we already
- * have it locked. In this case we just increment the lock
- * recursion count and return the inode to the caller.
- * Assert that the inode is already locked in the mode requested
- * by the caller. We cannot do lock promotions yet, so
- * die if someone gets this wrong.
- */
- if ((ip = xfs_inode_incore(tp->t_mountp, ino, tp)) != NULL) {
- /*
- * Make sure that the inode lock is held EXCL and
- * that the io lock is never upgraded when the inode
- * is already a part of the transaction.
- */
- ASSERT(ip->i_itemp != NULL);
- ASSERT(lock_flags & XFS_ILOCK_EXCL);
- ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
- ASSERT((!(lock_flags & XFS_IOLOCK_EXCL)) ||
- xfs_isilocked(ip, XFS_IOLOCK_EXCL));
- ASSERT((!(lock_flags & XFS_IOLOCK_EXCL)) ||
- (ip->i_itemp->ili_flags & XFS_ILI_IOLOCKED_EXCL));
- ASSERT((!(lock_flags & XFS_IOLOCK_SHARED)) ||
- xfs_isilocked(ip, XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED));
- ASSERT((!(lock_flags & XFS_IOLOCK_SHARED)) ||
- (ip->i_itemp->ili_flags & XFS_ILI_IOLOCKED_ANY));
-
- if (lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) {
- ip->i_itemp->ili_iolock_recur++;
- }
- if (lock_flags & XFS_ILOCK_EXCL) {
- ip->i_itemp->ili_ilock_recur++;
- }
- *ipp = ip;
- return 0;
- }
-
- ASSERT(lock_flags & XFS_ILOCK_EXCL);
- error = xfs_iget(tp->t_mountp, tp, ino, flags, lock_flags, &ip, 0);
- if (error) {
- return error;
- }
- ASSERT(ip != NULL);
- xfs_trans_ijoin(tp, ip, lock_flags);
- *ipp = ip;
- return 0;
+ error = xfs_iget(mp, tp, ino, flags, lock_flags, ipp, 0);
+ if (!error && tp)
+ xfs_trans_ijoin(tp, *ipp, lock_flags);
+ return error;
}
/*
@@ -163,8 +89,6 @@ xfs_trans_ijoin(
xfs_inode_item_init(ip, ip->i_mount);
iip = ip->i_itemp;
ASSERT(iip->ili_flags == 0);
- ASSERT(iip->ili_ilock_recur == 0);
- ASSERT(iip->ili_iolock_recur == 0);
/*
* Get a log_item_desc to point at the new item.
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