xfs: Fix deadlock between AGI and AGF when target_ip exists in xfs_rename()
When target_ip exists in xfs_rename(), the xfs_dir_replace() call may need to hold the AGF lock to allocate more blocks, and then invoking the xfs_droplink() call to hold AGI lock to drop target_ip onto the unlinked list, so we get the lock order AGF->AGI. This would break the ordering constraint on AGI and AGF locking - inode allocation locks the AGI, then can allocate a new extent for new inodes, locking the AGF after the AGI. In this patch we check whether the replace operation need more blocks firstly. If so, acquire the agi lock firstly to preserve locking order(AGI/AGF). Actually, the locking order problem only occurs when we are locking the AGI/AGF of the same AG. For multiple AGs the AGI lock will be released after the transaction committed. Signed-off-by:kaixuxia <kaixuxia@tencent.com> Reviewed-by:
Darrick J. Wong <darrick.wong@oracle.com> [darrick: reword the comment] Signed-off-by:
Darrick J. Wong <darrick.wong@oracle.com>
parent
048a35d2
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