diff options
| -rw-r--r-- | fs/xfs/xfs_reflink.c | 232 |
1 files changed, 138 insertions, 94 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 322a852ce284..c5b4fa004ca4 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -623,54 +623,47 @@ out: } /* - * Remap parts of a file's data fork after a successful CoW. + * Remap part of the CoW fork into the data fork. + * + * We aim to remap the range starting at @offset_fsb and ending at @end_fsb + * into the data fork; this function will remap what it can (at the end of the + * range) and update @end_fsb appropriately. Each remap gets its own + * transaction because we can end up merging and splitting bmbt blocks for + * every remap operation and we'd like to keep the block reservation + * requirements as low as possible. */ -int -xfs_reflink_end_cow( - struct xfs_inode *ip, - xfs_off_t offset, - xfs_off_t count) +STATIC int +xfs_reflink_end_cow_extent( + struct xfs_inode *ip, + xfs_fileoff_t offset_fsb, + xfs_fileoff_t *end_fsb) { - struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); - struct xfs_bmbt_irec got, del; - struct xfs_trans *tp; - xfs_fileoff_t offset_fsb; - xfs_fileoff_t end_fsb; - int error; - unsigned int resblks; - xfs_filblks_t rlen; - struct xfs_iext_cursor icur; - - trace_xfs_reflink_end_cow(ip, offset, count); + struct xfs_bmbt_irec got, del; + struct xfs_iext_cursor icur; + struct xfs_mount *mp = ip->i_mount; + struct xfs_trans *tp; + struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK); + xfs_filblks_t rlen; + unsigned int resblks; + int error; /* No COW extents? That's easy! */ - if (ifp->if_bytes == 0) + if (ifp->if_bytes == 0) { + *end_fsb = offset_fsb; return 0; + } - offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); - end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count); + resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK); + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, + XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp); + if (error) + return error; /* - * Start a rolling transaction to switch the mappings. We're - * unlikely ever to have to remap 16T worth of single-block - * extents, so just cap the worst case extent count to 2^32-1. - * Stick a warning in just in case, and avoid 64-bit division. + * Lock the inode. We have to ijoin without automatic unlock because + * the lead transaction is the refcountbt record deletion; the data + * fork update follows as a deferred log item. */ - BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX); - if (end_fsb - offset_fsb > UINT_MAX) { - error = -EFSCORRUPTED; - xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE); - ASSERT(0); - goto out; - } - resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount, - (unsigned int)(end_fsb - offset_fsb), - XFS_DATA_FORK); - error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write, - resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp); - if (error) - goto out; - xfs_ilock(ip, XFS_ILOCK_EXCL); xfs_trans_ijoin(tp, ip, 0); @@ -679,80 +672,131 @@ xfs_reflink_end_cow( * left by the time I/O completes for the loser of the race. In that * case we are done. */ - if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got)) + if (!xfs_iext_lookup_extent_before(ip, ifp, end_fsb, &icur, &got) || + got.br_startoff + got.br_blockcount <= offset_fsb) { + *end_fsb = offset_fsb; goto out_cancel; + } - /* Walk backwards until we're out of the I/O range... */ - while (got.br_startoff + got.br_blockcount > offset_fsb) { - del = got; - xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb); - - /* Extent delete may have bumped ext forward */ - if (!del.br_blockcount) - goto prev_extent; + /* + * Structure copy @got into @del, then trim @del to the range that we + * were asked to remap. We preserve @got for the eventual CoW fork + * deletion; from now on @del represents the mapping that we're + * actually remapping. + */ + del = got; + xfs_trim_extent(&del, offset_fsb, *end_fsb - offset_fsb); - /* - * Only remap real extent that contain data. With AIO - * speculatively preallocations can leak into the range we - * are called upon, and we need to skip them. - */ - if (!xfs_bmap_is_real_extent(&got)) - goto prev_extent; + ASSERT(del.br_blockcount > 0); - /* Unmap the old blocks in the data fork. */ - ASSERT(tp->t_firstblock == NULLFSBLOCK); - rlen = del.br_blockcount; - error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1); - if (error) - goto out_cancel; + /* + * Only remap real extents that contain data. With AIO, speculative + * preallocations can leak into the range we are called upon, and we + * need to skip them. + */ + if (!xfs_bmap_is_real_extent(&got)) { + *end_fsb = del.br_startoff; + goto out_cancel; + } - /* Trim the extent to whatever got unmapped. */ - if (rlen) { - xfs_trim_extent(&del, del.br_startoff + rlen, - del.br_blockcount - rlen); - } - trace_xfs_reflink_cow_remap(ip, &del); + /* Unmap the old blocks in the data fork. */ + rlen = del.br_blockcount; + error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1); + if (error) + goto out_cancel; - /* Free the CoW orphan record. */ - error = xfs_refcount_free_cow_extent(tp, del.br_startblock, - del.br_blockcount); - if (error) - goto out_cancel; + /* Trim the extent to whatever got unmapped. */ + xfs_trim_extent(&del, del.br_startoff + rlen, del.br_blockcount - rlen); + trace_xfs_reflink_cow_remap(ip, &del); - /* Map the new blocks into the data fork. */ - error = xfs_bmap_map_extent(tp, ip, &del); - if (error) - goto out_cancel; + /* Free the CoW orphan record. */ + error = xfs_refcount_free_cow_extent(tp, del.br_startblock, + del.br_blockcount); + if (error) + goto out_cancel; - /* Charge this new data fork mapping to the on-disk quota. */ - xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT, - (long)del.br_blockcount); + /* Map the new blocks into the data fork. */ + error = xfs_bmap_map_extent(tp, ip, &del); + if (error) + goto out_cancel; - /* Remove the mapping from the CoW fork. */ - xfs_bmap_del_extent_cow(ip, &icur, &got, &del); + /* Charge this new data fork mapping to the on-disk quota. */ + xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT, + (long)del.br_blockcount); - error = xfs_defer_finish(&tp); - if (error) - goto out_cancel; - if (!xfs_iext_get_extent(ifp, &icur, &got)) - break; - continue; -prev_extent: - if (!xfs_iext_prev_extent(ifp, &icur, &got)) - break; - } + /* Remove the mapping from the CoW fork. */ + xfs_bmap_del_extent_cow(ip, &icur, &got, &del); error = xfs_trans_commit(tp); xfs_iunlock(ip, XFS_ILOCK_EXCL); if (error) - goto out; + return error; + + /* Update the caller about how much progress we made. */ + *end_fsb = del.br_startoff; return 0; out_cancel: xfs_trans_cancel(tp); xfs_iunlock(ip, XFS_ILOCK_EXCL); -out: - trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_); + return error; +} + +/* + * Remap parts of a file's data fork after a successful CoW. + */ +int +xfs_reflink_end_cow( + struct xfs_inode *ip, + xfs_off_t offset, + xfs_off_t count) +{ + xfs_fileoff_t offset_fsb; + xfs_fileoff_t end_fsb; + int error = 0; + + trace_xfs_reflink_end_cow(ip, offset, count); + + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); + end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count); + + /* + * Walk backwards until we're out of the I/O range. The loop function + * repeatedly cycles the ILOCK to allocate one transaction per remapped + * extent. + * + * If we're being called by writeback then the the pages will still + * have PageWriteback set, which prevents races with reflink remapping + * and truncate. Reflink remapping prevents races with writeback by + * taking the iolock and mmaplock before flushing the pages and + * remapping, which means there won't be any further writeback or page + * cache dirtying until the reflink completes. + * + * We should never have two threads issuing writeback for the same file + * region. There are also have post-eof checks in the writeback + * preparation code so that we don't bother writing out pages that are + * about to be truncated. + * + * If we're being called as part of directio write completion, the dio + * count is still elevated, which reflink and truncate will wait for. + * Reflink remapping takes the iolock and mmaplock and waits for + * pending dio to finish, which should prevent any directio until the + * remap completes. Multiple concurrent directio writes to the same + * region are handled by end_cow processing only occurring for the + * threads which succeed; the outcome of multiple overlapping direct + * writes is not well defined anyway. + * + * It's possible that a buffered write and a direct write could collide + * here (the buffered write stumbles in after the dio flushes and + * invalidates the page cache and immediately queues writeback), but we + * have never supported this 100%. If either disk write succeeds the + * blocks will be remapped. + */ + while (end_fsb > offset_fsb && !error) + error = xfs_reflink_end_cow_extent(ip, offset_fsb, &end_fsb); + + if (error) + trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_); return error; } |