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xfs: fix broken MAXREFCOUNT handling
This series fixes a bug in the refcount code where we don't merge records correctly if the refcount is hovering around MAXREFCOUNT. This fixes regressions in xfs/179 when fsdax is enabled. xfs/179 itself will be modified to exploit the bug through the pagecache path. Signed-off-by: Darrick J. Wong <djwong@kernel.org> -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEUzaAxoMeQq6m2jMV+H93GTRKtOsFAmOI5VUACgkQ+H93GTRK tOsf+A/9GsOyXhF2dAPt2zvDpoiHvR/y42/LQUoKah2cxUXOhfPIu53xoRgNgNOh 1O3D1s9HjudI1Bo6/R+xeijq/upKGmKmOJL52vULy8UqsbDLvV8RHQ5YfHbIIghW HiYsD3aX5qhTKr7KHMrJzZcokSTAIGgIAT3QK7X0BrWUSXK12BN53A5D3XSFEMPu K1rws+XEZkOlgNti1DqTrRa6OdU+Y0CKOobNciNGTEBi6Gg4QFaudoobrBAYGNpQ R2icLAJG2lxlv3VRr2GqfgZ4XFh+q8TmXfb0tF+/rS/XWeDoElci+t4zpyDyeetH H4IdfXuiJMw9UUj8h7N299qRYlUFhfqfwMs/9FBU+W8UTV9ke6796r+/3ARcUino GoHwNpXEQZHatU5zVj1v2/6yVOCLapoz1WHa3pkbvwBGPKvWS2DGs0Mx5W28b/QE M/uRj/CL4re0lEqsnNHu0J2tMiLb5A33pkdAZTfsoOwXdjpZdiXCuUHJzD71UDb8 hePXm5c9XBSSLIV44bpgBCDqu7acybENRUXJ2+1kBebxaKEpH8nrPKIuHRzX2Ulh KfCZwwMLR24AYYHcFRsb8p4QtBaSu0jF4WJQJoggSsHErQfDdNDfTr5nL86kF+3P zp9/8WOi4ZfRGAMOS/kTjZRFnG+hDE+EqvAzuNyf9vlytF84KZU= =qgYH -----END PGP SIGNATURE----- Merge tag 'maxrefcount-fixes-6.2_2022-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.2-mergeD xfs: fix broken MAXREFCOUNT handling This series fixes a bug in the refcount code where we don't merge records correctly if the refcount is hovering around MAXREFCOUNT. This fixes regressions in xfs/179 when fsdax is enabled. xfs/179 itself will be modified to exploit the bug through the pagecache path. Signed-off-by: Darrick J. Wong <djwong@kernel.org> * tag 'maxrefcount-fixes-6.2_2022-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux: xfs: estimate post-merge refcounts correctly xfs: hoist refcount record merge predicates
This commit is contained in:
Darrick J. Wong
commit
948961964b
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@ -815,11 +815,136 @@ out_error:
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/* Is this extent valid? */
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static inline bool
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xfs_refc_valid(
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struct xfs_refcount_irec *rc)
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const struct xfs_refcount_irec *rc)
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{
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return rc->rc_startblock != NULLAGBLOCK;
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}
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static inline xfs_nlink_t
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xfs_refc_merge_refcount(
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const struct xfs_refcount_irec *irec,
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enum xfs_refc_adjust_op adjust)
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{
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/* Once a record hits MAXREFCOUNT, it is pinned there forever */
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if (irec->rc_refcount == MAXREFCOUNT)
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return MAXREFCOUNT;
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return irec->rc_refcount + adjust;
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}
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static inline bool
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xfs_refc_want_merge_center(
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const struct xfs_refcount_irec *left,
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const struct xfs_refcount_irec *cleft,
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const struct xfs_refcount_irec *cright,
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const struct xfs_refcount_irec *right,
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bool cleft_is_cright,
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enum xfs_refc_adjust_op adjust,
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unsigned long long *ulenp)
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{
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unsigned long long ulen = left->rc_blockcount;
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xfs_nlink_t new_refcount;
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/*
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* To merge with a center record, both shoulder records must be
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* adjacent to the record we want to adjust. This is only true if
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* find_left and find_right made all four records valid.
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*/
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if (!xfs_refc_valid(left) || !xfs_refc_valid(right) ||
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!xfs_refc_valid(cleft) || !xfs_refc_valid(cright))
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return false;
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/* There must only be one record for the entire range. */
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if (!cleft_is_cright)
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return false;
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/* The shoulder record refcounts must match the new refcount. */
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new_refcount = xfs_refc_merge_refcount(cleft, adjust);
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if (left->rc_refcount != new_refcount)
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return false;
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if (right->rc_refcount != new_refcount)
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return false;
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/*
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* The new record cannot exceed the max length. ulen is a ULL as the
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* individual record block counts can be up to (u32 - 1) in length
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* hence we need to catch u32 addition overflows here.
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*/
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ulen += cleft->rc_blockcount + right->rc_blockcount;
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if (ulen >= MAXREFCEXTLEN)
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return false;
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*ulenp = ulen;
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return true;
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}
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static inline bool
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xfs_refc_want_merge_left(
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const struct xfs_refcount_irec *left,
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const struct xfs_refcount_irec *cleft,
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enum xfs_refc_adjust_op adjust)
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{
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unsigned long long ulen = left->rc_blockcount;
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xfs_nlink_t new_refcount;
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/*
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* For a left merge, the left shoulder record must be adjacent to the
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* start of the range. If this is true, find_left made left and cleft
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* contain valid contents.
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*/
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if (!xfs_refc_valid(left) || !xfs_refc_valid(cleft))
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return false;
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/* Left shoulder record refcount must match the new refcount. */
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new_refcount = xfs_refc_merge_refcount(cleft, adjust);
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if (left->rc_refcount != new_refcount)
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return false;
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/*
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* The new record cannot exceed the max length. ulen is a ULL as the
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* individual record block counts can be up to (u32 - 1) in length
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* hence we need to catch u32 addition overflows here.
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*/
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ulen += cleft->rc_blockcount;
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if (ulen >= MAXREFCEXTLEN)
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return false;
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return true;
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}
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static inline bool
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xfs_refc_want_merge_right(
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const struct xfs_refcount_irec *cright,
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const struct xfs_refcount_irec *right,
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enum xfs_refc_adjust_op adjust)
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{
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unsigned long long ulen = right->rc_blockcount;
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xfs_nlink_t new_refcount;
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/*
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* For a right merge, the right shoulder record must be adjacent to the
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* end of the range. If this is true, find_right made cright and right
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* contain valid contents.
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*/
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if (!xfs_refc_valid(right) || !xfs_refc_valid(cright))
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return false;
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/* Right shoulder record refcount must match the new refcount. */
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new_refcount = xfs_refc_merge_refcount(cright, adjust);
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if (right->rc_refcount != new_refcount)
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return false;
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/*
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* The new record cannot exceed the max length. ulen is a ULL as the
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* individual record block counts can be up to (u32 - 1) in length
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* hence we need to catch u32 addition overflows here.
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*/
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ulen += cright->rc_blockcount;
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if (ulen >= MAXREFCEXTLEN)
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return false;
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return true;
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}
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/*
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* Try to merge with any extents on the boundaries of the adjustment range.
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*/
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@ -861,23 +986,15 @@ xfs_refcount_merge_extents(
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(cleft.rc_blockcount == cright.rc_blockcount);
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/* Try to merge left, cleft, and right. cleft must == cright. */
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ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount +
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right.rc_blockcount;
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if (xfs_refc_valid(&left) && xfs_refc_valid(&right) &&
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xfs_refc_valid(&cleft) && xfs_refc_valid(&cright) && cequal &&
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left.rc_refcount == cleft.rc_refcount + adjust &&
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right.rc_refcount == cleft.rc_refcount + adjust &&
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ulen < MAXREFCEXTLEN) {
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if (xfs_refc_want_merge_center(&left, &cleft, &cright, &right, cequal,
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adjust, &ulen)) {
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*shape_changed = true;
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return xfs_refcount_merge_center_extents(cur, &left, &cleft,
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&right, ulen, aglen);
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}
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/* Try to merge left and cleft. */
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ulen = (unsigned long long)left.rc_blockcount + cleft.rc_blockcount;
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if (xfs_refc_valid(&left) && xfs_refc_valid(&cleft) &&
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left.rc_refcount == cleft.rc_refcount + adjust &&
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ulen < MAXREFCEXTLEN) {
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if (xfs_refc_want_merge_left(&left, &cleft, adjust)) {
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*shape_changed = true;
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error = xfs_refcount_merge_left_extent(cur, &left, &cleft,
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agbno, aglen);
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@ -893,10 +1010,7 @@ xfs_refcount_merge_extents(
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}
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/* Try to merge cright and right. */
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ulen = (unsigned long long)right.rc_blockcount + cright.rc_blockcount;
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if (xfs_refc_valid(&right) && xfs_refc_valid(&cright) &&
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right.rc_refcount == cright.rc_refcount + adjust &&
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ulen < MAXREFCEXTLEN) {
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if (xfs_refc_want_merge_right(&cright, &right, adjust)) {
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*shape_changed = true;
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return xfs_refcount_merge_right_extent(cur, &right, &cright,
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aglen);
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