summaryrefslogtreecommitdiff
path: root/fs/xfs/xfs_reflink.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/xfs/xfs_reflink.c')
-rw-r--r--fs/xfs/xfs_reflink.c428
1 files changed, 428 insertions, 0 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 0aac262..c1e98a4 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -792,3 +792,431 @@ xfs_reflink_recover_cow(
return error;
}
+
+/*
+ * Reflinking (Block) Ranges of Two Files Together
+ *
+ * First, ensure that the reflink flag is set on both inodes. The flag is an
+ * optimization to avoid unnecessary refcount btree lookups in the write path.
+ *
+ * Now we can iteratively remap the range of extents (and holes) in src to the
+ * corresponding ranges in dest. Let drange and srange denote the ranges of
+ * logical blocks in dest and src touched by the reflink operation.
+ *
+ * While the length of drange is greater than zero,
+ * - Read src's bmbt at the start of srange ("imap")
+ * - If imap doesn't exist, make imap appear to start at the end of srange
+ * with zero length.
+ * - If imap starts before srange, advance imap to start at srange.
+ * - If imap goes beyond srange, truncate imap to end at the end of srange.
+ * - Punch (imap start - srange start + imap len) blocks from dest at
+ * offset (drange start).
+ * - If imap points to a real range of pblks,
+ * > Increase the refcount of the imap's pblks
+ * > Map imap's pblks into dest at the offset
+ * (drange start + imap start - srange start)
+ * - Advance drange and srange by (imap start - srange start + imap len)
+ *
+ * Finally, if the reflink made dest longer, update both the in-core and
+ * on-disk file sizes.
+ *
+ * ASCII Art Demonstration:
+ *
+ * Let's say we want to reflink this source file:
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS (src file)
+ * <-------------------->
+ *
+ * into this destination file:
+ *
+ * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
+ * <-------------------->
+ * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
+ * Observe that the range has different logical offsets in either file.
+ *
+ * Consider that the first extent in the source file doesn't line up with our
+ * reflink range. Unmapping and remapping are separate operations, so we can
+ * unmap more blocks from the destination file than we remap.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <------->
+ * --DDDDD---------DDDDD--DDD
+ * <------->
+ *
+ * Now remap the source extent into the destination file:
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <------->
+ * --DDDDD--SSSSSSSDDDDD--DDD
+ * <------->
+ *
+ * Do likewise with the second hole and extent in our range. Holes in the
+ * unmap range don't affect our operation.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <---->
+ * --DDDDD--SSSSSSS-SSSSS-DDD
+ * <---->
+ *
+ * Finally, unmap and remap part of the third extent. This will increase the
+ * size of the destination file.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <----->
+ * --DDDDD--SSSSSSS-SSSSS----SSS
+ * <----->
+ *
+ * Once we update the destination file's i_size, we're done.
+ */
+
+/*
+ * Ensure the reflink bit is set in both inodes.
+ */
+STATIC int
+xfs_reflink_set_inode_flag(
+ struct xfs_inode *src,
+ struct xfs_inode *dest)
+{
+ struct xfs_mount *mp = src->i_mount;
+ int error;
+ struct xfs_trans *tp;
+
+ if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
+ return 0;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ goto out_error;
+
+ /* Lock both files against IO */
+ if (src->i_ino == dest->i_ino)
+ xfs_ilock(src, XFS_ILOCK_EXCL);
+ else
+ xfs_lock_two_inodes(src, dest, XFS_ILOCK_EXCL);
+
+ if (!xfs_is_reflink_inode(src)) {
+ trace_xfs_reflink_set_inode_flag(src);
+ xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
+ src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
+ xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
+ xfs_ifork_init_cow(src);
+ } else
+ xfs_iunlock(src, XFS_ILOCK_EXCL);
+
+ if (src->i_ino == dest->i_ino)
+ goto commit_flags;
+
+ if (!xfs_is_reflink_inode(dest)) {
+ trace_xfs_reflink_set_inode_flag(dest);
+ xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
+ dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
+ xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
+ xfs_ifork_init_cow(dest);
+ } else
+ xfs_iunlock(dest, XFS_ILOCK_EXCL);
+
+commit_flags:
+ error = xfs_trans_commit(tp);
+ if (error)
+ goto out_error;
+ return error;
+
+out_error:
+ trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Update destination inode size, if necessary.
+ */
+STATIC int
+xfs_reflink_update_dest(
+ struct xfs_inode *dest,
+ xfs_off_t newlen)
+{
+ struct xfs_mount *mp = dest->i_mount;
+ struct xfs_trans *tp;
+ int error;
+
+ if (newlen <= i_size_read(VFS_I(dest)))
+ return 0;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ goto out_error;
+
+ xfs_ilock(dest, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
+
+ trace_xfs_reflink_update_inode_size(dest, newlen);
+ i_size_write(VFS_I(dest), newlen);
+ dest->i_d.di_size = newlen;
+ xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
+
+ error = xfs_trans_commit(tp);
+ if (error)
+ goto out_error;
+ return error;
+
+out_error:
+ trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Unmap a range of blocks from a file, then map other blocks into the hole.
+ * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
+ * The extent irec is mapped into dest at irec->br_startoff.
+ */
+STATIC int
+xfs_reflink_remap_extent(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *irec,
+ xfs_fileoff_t destoff,
+ xfs_off_t new_isize)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_trans *tp;
+ xfs_fsblock_t firstfsb;
+ unsigned int resblks;
+ struct xfs_defer_ops dfops;
+ struct xfs_bmbt_irec uirec;
+ bool real_extent;
+ xfs_filblks_t rlen;
+ xfs_filblks_t unmap_len;
+ xfs_off_t newlen;
+ int error;
+
+ unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
+ trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
+
+ /* Only remap normal extents. */
+ real_extent = (irec->br_startblock != HOLESTARTBLOCK &&
+ irec->br_startblock != DELAYSTARTBLOCK &&
+ !ISUNWRITTEN(irec));
+
+ /* Start a rolling transaction to switch the mappings */
+ resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+ if (error)
+ goto out;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, 0);
+
+ /* If we're not just clearing space, then do we have enough quota? */
+ if (real_extent) {
+ error = xfs_trans_reserve_quota_nblks(tp, ip,
+ irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
+ if (error)
+ goto out_cancel;
+ }
+
+ trace_xfs_reflink_remap(ip, irec->br_startoff,
+ irec->br_blockcount, irec->br_startblock);
+
+ /* Unmap the old blocks in the data fork. */
+ rlen = unmap_len;
+ while (rlen) {
+ xfs_defer_init(&dfops, &firstfsb);
+ error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1,
+ &firstfsb, &dfops);
+ if (error)
+ goto out_defer;
+
+ /*
+ * Trim the extent to whatever got unmapped.
+ * Remember, bunmapi works backwards.
+ */
+ uirec.br_startblock = irec->br_startblock + rlen;
+ uirec.br_startoff = irec->br_startoff + rlen;
+ uirec.br_blockcount = unmap_len - rlen;
+ unmap_len = rlen;
+
+ /* If this isn't a real mapping, we're done. */
+ if (!real_extent || uirec.br_blockcount == 0)
+ goto next_extent;
+
+ trace_xfs_reflink_remap(ip, uirec.br_startoff,
+ uirec.br_blockcount, uirec.br_startblock);
+
+ /* Update the refcount tree */
+ error = xfs_refcount_increase_extent(mp, &dfops, &uirec);
+ if (error)
+ goto out_defer;
+
+ /* Map the new blocks into the data fork. */
+ error = xfs_bmap_map_extent(mp, &dfops, ip, &uirec);
+ if (error)
+ goto out_defer;
+
+ /* Update quota accounting. */
+ xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
+ uirec.br_blockcount);
+
+ /* Update dest isize if needed. */
+ newlen = XFS_FSB_TO_B(mp,
+ uirec.br_startoff + uirec.br_blockcount);
+ newlen = min_t(xfs_off_t, newlen, new_isize);
+ if (newlen > i_size_read(VFS_I(ip))) {
+ trace_xfs_reflink_update_inode_size(ip, newlen);
+ i_size_write(VFS_I(ip), newlen);
+ ip->i_d.di_size = newlen;
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ }
+
+next_extent:
+ /* Process all the deferred stuff. */
+ error = xfs_defer_finish(&tp, &dfops, ip);
+ if (error)
+ goto out_defer;
+ }
+
+ error = xfs_trans_commit(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (error)
+ goto out;
+ return 0;
+
+out_defer:
+ xfs_defer_cancel(&dfops);
+out_cancel:
+ xfs_trans_cancel(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+ trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Iteratively remap one file's extents (and holes) to another's.
+ */
+STATIC int
+xfs_reflink_remap_blocks(
+ struct xfs_inode *src,
+ xfs_fileoff_t srcoff,
+ struct xfs_inode *dest,
+ xfs_fileoff_t destoff,
+ xfs_filblks_t len,
+ xfs_off_t new_isize)
+{
+ struct xfs_bmbt_irec imap;
+ int nimaps;
+ int error = 0;
+ xfs_filblks_t range_len;
+
+ /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
+ while (len) {
+ trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
+ dest, destoff);
+ /* Read extent from the source file */
+ nimaps = 1;
+ xfs_ilock(src, XFS_ILOCK_EXCL);
+ error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
+ xfs_iunlock(src, XFS_ILOCK_EXCL);
+ if (error)
+ goto err;
+ ASSERT(nimaps == 1);
+
+ trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
+ &imap);
+
+ /* Translate imap into the destination file. */
+ range_len = imap.br_startoff + imap.br_blockcount - srcoff;
+ imap.br_startoff += destoff - srcoff;
+
+ /* Clear dest from destoff to the end of imap and map it in. */
+ error = xfs_reflink_remap_extent(dest, &imap, destoff,
+ new_isize);
+ if (error)
+ goto err;
+
+ if (fatal_signal_pending(current)) {
+ error = -EINTR;
+ goto err;
+ }
+
+ /* Advance drange/srange */
+ srcoff += range_len;
+ destoff += range_len;
+ len -= range_len;
+ }
+
+ return 0;
+
+err:
+ trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Link a range of blocks from one file to another.
+ */
+int
+xfs_reflink_remap_range(
+ struct xfs_inode *src,
+ xfs_off_t srcoff,
+ struct xfs_inode *dest,
+ xfs_off_t destoff,
+ xfs_off_t len)
+{
+ struct xfs_mount *mp = src->i_mount;
+ xfs_fileoff_t sfsbno, dfsbno;
+ xfs_filblks_t fsblen;
+ int error;
+
+ if (!xfs_sb_version_hasreflink(&mp->m_sb))
+ return -EOPNOTSUPP;
+
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
+ /* Don't reflink realtime inodes */
+ if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
+ return -EINVAL;
+
+ trace_xfs_reflink_remap_range(src, srcoff, len, dest, destoff);
+
+ /* Lock both files against IO */
+ if (src->i_ino == dest->i_ino) {
+ xfs_ilock(src, XFS_IOLOCK_EXCL);
+ xfs_ilock(src, XFS_MMAPLOCK_EXCL);
+ } else {
+ xfs_lock_two_inodes(src, dest, XFS_IOLOCK_EXCL);
+ xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL);
+ }
+
+ error = xfs_reflink_set_inode_flag(src, dest);
+ if (error)
+ goto out_error;
+
+ /*
+ * Invalidate the page cache so that we can clear any CoW mappings
+ * in the destination file.
+ */
+ truncate_inode_pages_range(&VFS_I(dest)->i_data, destoff,
+ PAGE_ALIGN(destoff + len) - 1);
+
+ dfsbno = XFS_B_TO_FSBT(mp, destoff);
+ sfsbno = XFS_B_TO_FSBT(mp, srcoff);
+ fsblen = XFS_B_TO_FSB(mp, len);
+ error = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
+ destoff + len);
+ if (error)
+ goto out_error;
+
+ error = xfs_reflink_update_dest(dest, destoff + len);
+ if (error)
+ goto out_error;
+
+out_error:
+ xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
+ xfs_iunlock(src, XFS_IOLOCK_EXCL);
+ if (src->i_ino != dest->i_ino) {
+ xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
+ xfs_iunlock(dest, XFS_IOLOCK_EXCL);
+ }
+ if (error)
+ trace_xfs_reflink_remap_range_error(dest, error, _RET_IP_);
+ return error;
+}
generated by cgit v0.10.2 at 2024-08-14 16:18:40 (GMT)