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Maxim Sobolev
479c98287e
flush_pagedep_deps() drops the soft updates lock while obtaining the vnode of a newly created directory with get_parent_vp(). The MKDIR_BODY dependency may complete during this interval, invalidating the diradd selected before the lock was dropped. Once the directory's allocdirect is retired, the lookup of its first block by block number in flush_newblk_dep() can find an older dependency for a previous use of the same physical block. The newblk hash is not unique by block number: when ffs_reallocblks() relocates a cluster, the completed allocindirs of the old blocks stay on the indirdep's ir_completehd until the indirect block pointer in the inode is written, while the old blocks are already free and may be allocated to a new directory. flush_newblk_dep() then finds a D_ALLOCINDIR where it expects a D_ALLOCDIRECT and panics with "flush_newblk_dep: Bad newblk". Retain the vnode returned by get_parent_vp(), reacquire the soft updates lock, and restart dependency selection. Use the retained vnode only when the newly selected MKDIR_BODY dependency refers to the same inode. Enter flush_newblk_dep() with the soft updates lock held and pass it the associated diradd. Recheck MKDIR_BODY after every operation that may drop the lock, so that completion during the helper's retry loop cannot result in another lookup of the retired allocation. Keep the vnode handling in flush_pagedep_deps(), which owns the retained vnode and the list of unfinished diradds, and move the dependency selection into flush_pagedep_deps1(). The latter never acquires or releases a vnode: it returns EJUSTRETURN with the inode number when it needs one, or with 0 when the retained vnode must be released first, and every call restarts the selection, so a vnode is only used for a diradd found while it was held. This also merges the two get_parent_vp() call sites. Every restart goes through that return: obtaining or releasing a vnode, and continuing after jwait() or getdirtybuf() had to wait with the softdep lock dropped. The diradds deferred on the unfinished list are put back on the pagedep's list before the lock is dropped for a restart, so that none are kept off it while other threads can run. Assert that flush_newblk_dep() is called with the vnode exclusively locked. This preserves the original newblk dependency ordering and retains the existing assertion for an active MKDIR_BODY dependency that resolves to an unexpected dependency type. PR: 297976 Reviewed by: kib Tested by: pho Sponsored by: Sippy Software, Inc. Differential revision: https://reviews.freebsd.org/D59356
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