diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_exchmaps.c')
| -rw-r--r-- | fs/xfs/libxfs/xfs_exchmaps.c | 1235 |
1 files changed, 1235 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_exchmaps.c b/fs/xfs/libxfs/xfs_exchmaps.c new file mode 100644 index 0000000000..2021396651 --- /dev/null +++ b/fs/xfs/libxfs/xfs_exchmaps.c @@ -0,0 +1,1235 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2020-2024 Oracle. All Rights Reserved. + * Author: Darrick J. Wong <djwong@kernel.org> + */ +#include "xfs.h" +#include "xfs_fs.h" +#include "xfs_shared.h" +#include "xfs_format.h" +#include "xfs_log_format.h" +#include "xfs_trans_resv.h" +#include "xfs_mount.h" +#include "xfs_defer.h" +#include "xfs_inode.h" +#include "xfs_trans.h" +#include "xfs_bmap.h" +#include "xfs_icache.h" +#include "xfs_quota.h" +#include "xfs_exchmaps.h" +#include "xfs_trace.h" +#include "xfs_bmap_btree.h" +#include "xfs_trans_space.h" +#include "xfs_error.h" +#include "xfs_errortag.h" +#include "xfs_health.h" +#include "xfs_exchmaps_item.h" +#include "xfs_da_format.h" +#include "xfs_da_btree.h" +#include "xfs_attr_leaf.h" +#include "xfs_attr.h" +#include "xfs_dir2_priv.h" +#include "xfs_dir2.h" +#include "xfs_symlink_remote.h" + +struct kmem_cache *xfs_exchmaps_intent_cache; + +/* bmbt mappings adjacent to a pair of records. */ +struct xfs_exchmaps_adjacent { + struct xfs_bmbt_irec left1; + struct xfs_bmbt_irec right1; + struct xfs_bmbt_irec left2; + struct xfs_bmbt_irec right2; +}; + +#define ADJACENT_INIT { \ + .left1 = { .br_startblock = HOLESTARTBLOCK }, \ + .right1 = { .br_startblock = HOLESTARTBLOCK }, \ + .left2 = { .br_startblock = HOLESTARTBLOCK }, \ + .right2 = { .br_startblock = HOLESTARTBLOCK }, \ +} + +/* Information to reset reflink flag / CoW fork state after an exchange. */ + +/* + * If the reflink flag is set on either inode, make sure it has an incore CoW + * fork, since all reflink inodes must have them. If there's a CoW fork and it + * has mappings in it, make sure the inodes are tagged appropriately so that + * speculative preallocations can be GC'd if we run low of space. + */ +static inline void +xfs_exchmaps_ensure_cowfork( + struct xfs_inode *ip) +{ + struct xfs_ifork *cfork; + + if (xfs_is_reflink_inode(ip)) + xfs_ifork_init_cow(ip); + + cfork = xfs_ifork_ptr(ip, XFS_COW_FORK); + if (!cfork) + return; + if (cfork->if_bytes > 0) + xfs_inode_set_cowblocks_tag(ip); + else + xfs_inode_clear_cowblocks_tag(ip); +} + +/* + * Adjust the on-disk inode size upwards if needed so that we never add + * mappings into the file past EOF. This is crucial so that log recovery won't + * get confused by the sudden appearance of post-eof mappings. + */ +STATIC void +xfs_exchmaps_update_size( + struct xfs_trans *tp, + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + xfs_fsize_t new_isize) +{ + struct xfs_mount *mp = tp->t_mountp; + xfs_fsize_t len; + + if (new_isize < 0) + return; + + len = min(XFS_FSB_TO_B(mp, imap->br_startoff + imap->br_blockcount), + new_isize); + + if (len <= ip->i_disk_size) + return; + + trace_xfs_exchmaps_update_inode_size(ip, len); + + ip->i_disk_size = len; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); +} + +/* Advance the incore state tracking after exchanging a mapping. */ +static inline void +xmi_advance( + struct xfs_exchmaps_intent *xmi, + const struct xfs_bmbt_irec *irec) +{ + xmi->xmi_startoff1 += irec->br_blockcount; + xmi->xmi_startoff2 += irec->br_blockcount; + xmi->xmi_blockcount -= irec->br_blockcount; +} + +/* Do we still have more mappings to exchange? */ +static inline bool +xmi_has_more_exchange_work(const struct xfs_exchmaps_intent *xmi) +{ + return xmi->xmi_blockcount > 0; +} + +/* Do we have post-operation cleanups to perform? */ +static inline bool +xmi_has_postop_work(const struct xfs_exchmaps_intent *xmi) +{ + return xmi->xmi_flags & (XFS_EXCHMAPS_CLEAR_INO1_REFLINK | + XFS_EXCHMAPS_CLEAR_INO2_REFLINK | + __XFS_EXCHMAPS_INO2_SHORTFORM); +} + +/* Check all mappings to make sure we can actually exchange them. */ +int +xfs_exchmaps_check_forks( + struct xfs_mount *mp, + const struct xfs_exchmaps_req *req) +{ + struct xfs_ifork *ifp1, *ifp2; + int whichfork = xfs_exchmaps_reqfork(req); + + /* No fork? */ + ifp1 = xfs_ifork_ptr(req->ip1, whichfork); + ifp2 = xfs_ifork_ptr(req->ip2, whichfork); + if (!ifp1 || !ifp2) + return -EINVAL; + + /* We don't know how to exchange local format forks. */ + if (ifp1->if_format == XFS_DINODE_FMT_LOCAL || + ifp2->if_format == XFS_DINODE_FMT_LOCAL) + return -EINVAL; + + return 0; +} + +#ifdef CONFIG_XFS_QUOTA +/* Log the actual updates to the quota accounting. */ +static inline void +xfs_exchmaps_update_quota( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi, + struct xfs_bmbt_irec *irec1, + struct xfs_bmbt_irec *irec2) +{ + int64_t ip1_delta = 0, ip2_delta = 0; + unsigned int qflag; + + qflag = XFS_IS_REALTIME_INODE(xmi->xmi_ip1) ? XFS_TRANS_DQ_RTBCOUNT : + XFS_TRANS_DQ_BCOUNT; + + if (xfs_bmap_is_real_extent(irec1)) { + ip1_delta -= irec1->br_blockcount; + ip2_delta += irec1->br_blockcount; + } + + if (xfs_bmap_is_real_extent(irec2)) { + ip1_delta += irec2->br_blockcount; + ip2_delta -= irec2->br_blockcount; + } + + xfs_trans_mod_dquot_byino(tp, xmi->xmi_ip1, qflag, ip1_delta); + xfs_trans_mod_dquot_byino(tp, xmi->xmi_ip2, qflag, ip2_delta); +} +#else +# define xfs_exchmaps_update_quota(tp, xmi, irec1, irec2) ((void)0) +#endif + +/* Decide if we want to skip this mapping from file1. */ +static inline bool +xfs_exchmaps_can_skip_mapping( + struct xfs_exchmaps_intent *xmi, + struct xfs_bmbt_irec *irec) +{ + struct xfs_mount *mp = xmi->xmi_ip1->i_mount; + + /* Do not skip this mapping if the caller did not tell us to. */ + if (!(xmi->xmi_flags & XFS_EXCHMAPS_INO1_WRITTEN)) + return false; + + /* Do not skip mapped, written mappings. */ + if (xfs_bmap_is_written_extent(irec)) + return false; + + /* + * The mapping is unwritten or a hole. It cannot be a delalloc + * reservation because we already excluded those. It cannot be an + * unwritten extent with dirty page cache because we flushed the page + * cache. For files where the allocation unit is 1FSB (files on the + * data dev, rt files if the extent size is 1FSB), we can safely + * skip this mapping. + */ + if (!xfs_inode_has_bigrtalloc(xmi->xmi_ip1)) + return true; + + /* + * For a realtime file with a multi-fsb allocation unit, the decision + * is trickier because we can only swap full allocation units. + * Unwritten mappings can appear in the middle of an rtx if the rtx is + * partially written, but they can also appear for preallocations. + * + * If the mapping is a hole, skip it entirely. Holes should align with + * rtx boundaries. + */ + if (!xfs_bmap_is_real_extent(irec)) + return true; + + /* + * All mappings below this point are unwritten. + * + * - If the beginning is not aligned to an rtx, trim the end of the + * mapping so that it does not cross an rtx boundary, and swap it. + * + * - If both ends are aligned to an rtx, skip the entire mapping. + */ + if (!isaligned_64(irec->br_startoff, mp->m_sb.sb_rextsize)) { + xfs_fileoff_t new_end; + + new_end = roundup_64(irec->br_startoff, mp->m_sb.sb_rextsize); + irec->br_blockcount = min(irec->br_blockcount, + new_end - irec->br_startoff); + return false; + } + if (isaligned_64(irec->br_blockcount, mp->m_sb.sb_rextsize)) + return true; + + /* + * All mappings below this point are unwritten, start on an rtx + * boundary, and do not end on an rtx boundary. + * + * - If the mapping is longer than one rtx, trim the end of the mapping + * down to an rtx boundary and skip it. + * + * - The mapping is shorter than one rtx. Swap it. + */ + if (irec->br_blockcount > mp->m_sb.sb_rextsize) { + xfs_fileoff_t new_end; + + new_end = rounddown_64(irec->br_startoff + irec->br_blockcount, + mp->m_sb.sb_rextsize); + irec->br_blockcount = new_end - irec->br_startoff; + return true; + } + + return false; +} + +/* + * Walk forward through the file ranges in @xmi until we find two different + * mappings to exchange. If there is work to do, return the mappings; + * otherwise we've reached the end of the range and xmi_blockcount will be + * zero. + * + * If the walk skips over a pair of mappings to the same storage, save them as + * the left records in @adj (if provided) so that the simulation phase can + * avoid an extra lookup. + */ +static int +xfs_exchmaps_find_mappings( + struct xfs_exchmaps_intent *xmi, + struct xfs_bmbt_irec *irec1, + struct xfs_bmbt_irec *irec2, + struct xfs_exchmaps_adjacent *adj) +{ + int nimaps; + int bmap_flags; + int error; + + bmap_flags = xfs_bmapi_aflag(xfs_exchmaps_whichfork(xmi)); + + for (; xmi_has_more_exchange_work(xmi); xmi_advance(xmi, irec1)) { + /* Read mapping from the first file */ + nimaps = 1; + error = xfs_bmapi_read(xmi->xmi_ip1, xmi->xmi_startoff1, + xmi->xmi_blockcount, irec1, &nimaps, + bmap_flags); + if (error) + return error; + if (nimaps != 1 || + irec1->br_startblock == DELAYSTARTBLOCK || + irec1->br_startoff != xmi->xmi_startoff1) { + /* + * We should never get no mapping or a delalloc mapping + * or something that doesn't match what we asked for, + * since the caller flushed both inodes and we hold the + * ILOCKs for both inodes. + */ + ASSERT(0); + return -EINVAL; + } + + if (xfs_exchmaps_can_skip_mapping(xmi, irec1)) { + trace_xfs_exchmaps_mapping1_skip(xmi->xmi_ip1, irec1); + continue; + } + + /* Read mapping from the second file */ + nimaps = 1; + error = xfs_bmapi_read(xmi->xmi_ip2, xmi->xmi_startoff2, + irec1->br_blockcount, irec2, &nimaps, + bmap_flags); + if (error) + return error; + if (nimaps != 1 || + irec2->br_startblock == DELAYSTARTBLOCK || + irec2->br_startoff != xmi->xmi_startoff2) { + /* + * We should never get no mapping or a delalloc mapping + * or something that doesn't match what we asked for, + * since the caller flushed both inodes and we hold the + * ILOCKs for both inodes. + */ + ASSERT(0); + return -EINVAL; + } + + /* + * We can only exchange as many blocks as the smaller of the + * two mapping maps. + */ + irec1->br_blockcount = min(irec1->br_blockcount, + irec2->br_blockcount); + + trace_xfs_exchmaps_mapping1(xmi->xmi_ip1, irec1); + trace_xfs_exchmaps_mapping2(xmi->xmi_ip2, irec2); + + /* We found something to exchange, so return it. */ + if (irec1->br_startblock != irec2->br_startblock) + return 0; + + /* + * Two mappings pointing to the same physical block must not + * have different states; that's filesystem corruption. Move + * on to the next mapping if they're both holes or both point + * to the same physical space extent. + */ + if (irec1->br_state != irec2->br_state) { + xfs_bmap_mark_sick(xmi->xmi_ip1, + xfs_exchmaps_whichfork(xmi)); + xfs_bmap_mark_sick(xmi->xmi_ip2, + xfs_exchmaps_whichfork(xmi)); + return -EFSCORRUPTED; + } + + /* + * Save the mappings if we're estimating work and skipping + * these identical mappings. + */ + if (adj) { + memcpy(&adj->left1, irec1, sizeof(*irec1)); + memcpy(&adj->left2, irec2, sizeof(*irec2)); + } + } + + return 0; +} + +/* Exchange these two mappings. */ +static void +xfs_exchmaps_one_step( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi, + struct xfs_bmbt_irec *irec1, + struct xfs_bmbt_irec *irec2) +{ + int whichfork = xfs_exchmaps_whichfork(xmi); + + xfs_exchmaps_update_quota(tp, xmi, irec1, irec2); + + /* Remove both mappings. */ + xfs_bmap_unmap_extent(tp, xmi->xmi_ip1, whichfork, irec1); + xfs_bmap_unmap_extent(tp, xmi->xmi_ip2, whichfork, irec2); + + /* + * Re-add both mappings. We exchange the file offsets between the two + * maps and add the opposite map, which has the effect of filling the + * logical offsets we just unmapped, but with with the physical mapping + * information exchanged. + */ + swap(irec1->br_startoff, irec2->br_startoff); + xfs_bmap_map_extent(tp, xmi->xmi_ip1, whichfork, irec2); + xfs_bmap_map_extent(tp, xmi->xmi_ip2, whichfork, irec1); + + /* Make sure we're not adding mappings past EOF. */ + if (whichfork == XFS_DATA_FORK) { + xfs_exchmaps_update_size(tp, xmi->xmi_ip1, irec2, + xmi->xmi_isize1); + xfs_exchmaps_update_size(tp, xmi->xmi_ip2, irec1, + xmi->xmi_isize2); + } + + /* + * Advance our cursor and exit. The caller (either defer ops or log + * recovery) will log the XMD item, and if *blockcount is nonzero, it + * will log a new XMI item for the remainder and call us back. + */ + xmi_advance(xmi, irec1); +} + +/* Convert inode2's leaf attr fork back to shortform, if possible.. */ +STATIC int +xfs_exchmaps_attr_to_sf( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi) +{ + struct xfs_da_args args = { + .dp = xmi->xmi_ip2, + .geo = tp->t_mountp->m_attr_geo, + .whichfork = XFS_ATTR_FORK, + .trans = tp, + .owner = xmi->xmi_ip2->i_ino, + }; + struct xfs_buf *bp; + int forkoff; + int error; + + if (!xfs_attr_is_leaf(xmi->xmi_ip2)) + return 0; + + error = xfs_attr3_leaf_read(tp, xmi->xmi_ip2, xmi->xmi_ip2->i_ino, 0, + &bp); + if (error) + return error; + + forkoff = xfs_attr_shortform_allfit(bp, xmi->xmi_ip2); + if (forkoff == 0) + return 0; + + return xfs_attr3_leaf_to_shortform(bp, &args, forkoff); +} + +/* Convert inode2's block dir fork back to shortform, if possible.. */ +STATIC int +xfs_exchmaps_dir_to_sf( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi) +{ + struct xfs_da_args args = { + .dp = xmi->xmi_ip2, + .geo = tp->t_mountp->m_dir_geo, + .whichfork = XFS_DATA_FORK, + .trans = tp, + .owner = xmi->xmi_ip2->i_ino, + }; + struct xfs_dir2_sf_hdr sfh; + struct xfs_buf *bp; + int size; + int error = 0; + + if (xfs_dir2_format(&args, &error) != XFS_DIR2_FMT_BLOCK) + return error; + + error = xfs_dir3_block_read(tp, xmi->xmi_ip2, xmi->xmi_ip2->i_ino, &bp); + if (error) + return error; + + size = xfs_dir2_block_sfsize(xmi->xmi_ip2, bp->b_addr, &sfh); + if (size > xfs_inode_data_fork_size(xmi->xmi_ip2)) + return 0; + + return xfs_dir2_block_to_sf(&args, bp, size, &sfh); +} + +/* Convert inode2's remote symlink target back to shortform, if possible. */ +STATIC int +xfs_exchmaps_link_to_sf( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi) +{ + struct xfs_inode *ip = xmi->xmi_ip2; + struct xfs_ifork *ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK); + char *buf; + int error; + + if (ifp->if_format == XFS_DINODE_FMT_LOCAL || + ip->i_disk_size > xfs_inode_data_fork_size(ip)) + return 0; + + /* Read the current symlink target into a buffer. */ + buf = kmalloc(ip->i_disk_size + 1, + GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL); + if (!buf) { + ASSERT(0); + return -ENOMEM; + } + + error = xfs_symlink_remote_read(ip, buf); + if (error) + goto free; + + /* Remove the blocks. */ + error = xfs_symlink_remote_truncate(tp, ip); + if (error) + goto free; + + /* Convert fork to local format and log our changes. */ + xfs_idestroy_fork(ifp); + ifp->if_bytes = 0; + ifp->if_format = XFS_DINODE_FMT_LOCAL; + xfs_init_local_fork(ip, XFS_DATA_FORK, buf, ip->i_disk_size); + xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE); +free: + kfree(buf); + return error; +} + +/* Clear the reflink flag after an exchange. */ +static inline void +xfs_exchmaps_clear_reflink( + struct xfs_trans *tp, + struct xfs_inode *ip) +{ + trace_xfs_reflink_unset_inode_flag(ip); + + ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); +} + +/* Finish whatever work might come after an exchange operation. */ +static int +xfs_exchmaps_do_postop_work( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi) +{ + if (xmi->xmi_flags & __XFS_EXCHMAPS_INO2_SHORTFORM) { + int error = 0; + + if (xmi->xmi_flags & XFS_EXCHMAPS_ATTR_FORK) + error = xfs_exchmaps_attr_to_sf(tp, xmi); + else if (S_ISDIR(VFS_I(xmi->xmi_ip2)->i_mode)) + error = xfs_exchmaps_dir_to_sf(tp, xmi); + else if (S_ISLNK(VFS_I(xmi->xmi_ip2)->i_mode)) + error = xfs_exchmaps_link_to_sf(tp, xmi); + xmi->xmi_flags &= ~__XFS_EXCHMAPS_INO2_SHORTFORM; + if (error) + return error; + } + + if (xmi->xmi_flags & XFS_EXCHMAPS_CLEAR_INO1_REFLINK) { + xfs_exchmaps_clear_reflink(tp, xmi->xmi_ip1); + xmi->xmi_flags &= ~XFS_EXCHMAPS_CLEAR_INO1_REFLINK; + } + + if (xmi->xmi_flags & XFS_EXCHMAPS_CLEAR_INO2_REFLINK) { + xfs_exchmaps_clear_reflink(tp, xmi->xmi_ip2); + xmi->xmi_flags &= ~XFS_EXCHMAPS_CLEAR_INO2_REFLINK; + } + + return 0; +} + +/* Finish one step in a mapping exchange operation, possibly relogging. */ +int +xfs_exchmaps_finish_one( + struct xfs_trans *tp, + struct xfs_exchmaps_intent *xmi) +{ + struct xfs_bmbt_irec irec1, irec2; + int error; + + if (xmi_has_more_exchange_work(xmi)) { + /* + * If the operation state says that some range of the files + * have not yet been exchanged, look for mappings in that range + * to exchange. If we find some mappings, exchange them. + */ + error = xfs_exchmaps_find_mappings(xmi, &irec1, &irec2, NULL); + if (error) + return error; + + if (xmi_has_more_exchange_work(xmi)) + xfs_exchmaps_one_step(tp, xmi, &irec1, &irec2); + + /* + * If the caller asked us to exchange the file sizes after the + * exchange and either we just exchanged the last mappings in + * the range or we didn't find anything to exchange, update the + * ondisk file sizes. + */ + if ((xmi->xmi_flags & XFS_EXCHMAPS_SET_SIZES) && + !xmi_has_more_exchange_work(xmi)) { + xmi->xmi_ip1->i_disk_size = xmi->xmi_isize1; + xmi->xmi_ip2->i_disk_size = xmi->xmi_isize2; + + xfs_trans_log_inode(tp, xmi->xmi_ip1, XFS_ILOG_CORE); + xfs_trans_log_inode(tp, xmi->xmi_ip2, XFS_ILOG_CORE); + } + } else if (xmi_has_postop_work(xmi)) { + /* + * Now that we're finished with the exchange operation, + * complete the post-op cleanup work. + */ + error = xfs_exchmaps_do_postop_work(tp, xmi); + if (error) + return error; + } + + if (XFS_TEST_ERROR(false, tp->t_mountp, XFS_ERRTAG_EXCHMAPS_FINISH_ONE)) + return -EIO; + + /* If we still have work to do, ask for a new transaction. */ + if (xmi_has_more_exchange_work(xmi) || xmi_has_postop_work(xmi)) { + trace_xfs_exchmaps_defer(tp->t_mountp, xmi); + return -EAGAIN; + } + + /* + * If we reach here, we've finished all the exchange work and the post + * operation work. The last thing we need to do before returning to + * the caller is to make sure that COW forks are set up correctly. + */ + if (!(xmi->xmi_flags & XFS_EXCHMAPS_ATTR_FORK)) { + xfs_exchmaps_ensure_cowfork(xmi->xmi_ip1); + xfs_exchmaps_ensure_cowfork(xmi->xmi_ip2); + } + + return 0; +} + +/* + * Compute the amount of bmbt blocks we should reserve for each file. In the + * worst case, each exchange will fill a hole with a new mapping, which could + * result in a btree split every time we add a new leaf block. + */ +static inline uint64_t +xfs_exchmaps_bmbt_blocks( + struct xfs_mount *mp, + const struct xfs_exchmaps_req *req) +{ + return howmany_64(req->nr_exchanges, + XFS_MAX_CONTIG_BMAPS_PER_BLOCK(mp)) * + XFS_EXTENTADD_SPACE_RES(mp, xfs_exchmaps_reqfork(req)); +} + +/* Compute the space we should reserve for the rmap btree expansions. */ +static inline uint64_t +xfs_exchmaps_rmapbt_blocks( + struct xfs_mount *mp, + const struct xfs_exchmaps_req *req) +{ + if (!xfs_has_rmapbt(mp)) + return 0; + if (XFS_IS_REALTIME_INODE(req->ip1)) + return 0; + + return howmany_64(req->nr_exchanges, + XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp)) * + XFS_RMAPADD_SPACE_RES(mp); +} + +/* Estimate the bmbt and rmapbt overhead required to exchange mappings. */ +int +xfs_exchmaps_estimate_overhead( + struct xfs_exchmaps_req *req) +{ + struct xfs_mount *mp = req->ip1->i_mount; + xfs_filblks_t bmbt_blocks; + xfs_filblks_t rmapbt_blocks; + xfs_filblks_t resblks = req->resblks; + + /* + * Compute the number of bmbt and rmapbt blocks we might need to handle + * the estimated number of exchanges. + */ + bmbt_blocks = xfs_exchmaps_bmbt_blocks(mp, req); + rmapbt_blocks = xfs_exchmaps_rmapbt_blocks(mp, req); + + trace_xfs_exchmaps_overhead(mp, bmbt_blocks, rmapbt_blocks); + + /* Make sure the change in file block count doesn't overflow. */ + if (check_add_overflow(req->ip1_bcount, bmbt_blocks, &req->ip1_bcount)) + return -EFBIG; + if (check_add_overflow(req->ip2_bcount, bmbt_blocks, &req->ip2_bcount)) + return -EFBIG; + + /* + * Add together the number of blocks we need to handle btree growth, + * then add it to the number of blocks we need to reserve to this + * transaction. + */ + if (check_add_overflow(resblks, bmbt_blocks, &resblks)) + return -ENOSPC; + if (check_add_overflow(resblks, bmbt_blocks, &resblks)) + return -ENOSPC; + if (check_add_overflow(resblks, rmapbt_blocks, &resblks)) + return -ENOSPC; + if (check_add_overflow(resblks, rmapbt_blocks, &resblks)) + return -ENOSPC; + + /* Can't actually reserve more than UINT_MAX blocks. */ + if (req->resblks > UINT_MAX) + return -ENOSPC; + + req->resblks = resblks; + trace_xfs_exchmaps_final_estimate(req); + return 0; +} + +/* Decide if we can merge two real mappings. */ +static inline bool +xmi_can_merge( + const struct xfs_bmbt_irec *b1, + const struct xfs_bmbt_irec *b2) +{ + /* Don't merge holes. */ + if (b1->br_startblock == HOLESTARTBLOCK || + b2->br_startblock == HOLESTARTBLOCK) + return false; + + /* We don't merge holes. */ + if (!xfs_bmap_is_real_extent(b1) || !xfs_bmap_is_real_extent(b2)) + return false; + + if (b1->br_startoff + b1->br_blockcount == b2->br_startoff && + b1->br_startblock + b1->br_blockcount == b2->br_startblock && + b1->br_state == b2->br_state && + b1->br_blockcount + b2->br_blockcount <= XFS_MAX_BMBT_EXTLEN) + return true; + + return false; +} + +/* + * Decide if we can merge three mappings. Caller must ensure all three + * mappings must not be holes or delalloc reservations. + */ +static inline bool +xmi_can_merge_all( + const struct xfs_bmbt_irec *l, + const struct xfs_bmbt_irec *m, + const struct xfs_bmbt_irec *r) +{ + xfs_filblks_t new_len; + + new_len = l->br_blockcount + m->br_blockcount + r->br_blockcount; + return new_len <= XFS_MAX_BMBT_EXTLEN; +} + +#define CLEFT_CONTIG 0x01 +#define CRIGHT_CONTIG 0x02 +#define CHOLE 0x04 +#define CBOTH_CONTIG (CLEFT_CONTIG | CRIGHT_CONTIG) + +#define NLEFT_CONTIG 0x10 +#define NRIGHT_CONTIG 0x20 +#define NHOLE 0x40 +#define NBOTH_CONTIG (NLEFT_CONTIG | NRIGHT_CONTIG) + +/* Estimate the effect of a single exchange on mapping count. */ +static inline int +xmi_delta_nextents_step( + struct xfs_mount *mp, + const struct xfs_bmbt_irec *left, + const struct xfs_bmbt_irec *curr, + const struct xfs_bmbt_irec *new, + const struct xfs_bmbt_irec *right) +{ + bool lhole, rhole, chole, nhole; + unsigned int state = 0; + int ret = 0; + + lhole = left->br_startblock == HOLESTARTBLOCK; + rhole = right->br_startblock == HOLESTARTBLOCK; + chole = curr->br_startblock == HOLESTARTBLOCK; + nhole = new->br_startblock == HOLESTARTBLOCK; + + if (chole) + state |= CHOLE; + if (!lhole && !chole && xmi_can_merge(left, curr)) + state |= CLEFT_CONTIG; + if (!rhole && !chole && xmi_can_merge(curr, right)) + state |= CRIGHT_CONTIG; + if ((state & CBOTH_CONTIG) == CBOTH_CONTIG && + !xmi_can_merge_all(left, curr, right)) + state &= ~CRIGHT_CONTIG; + + if (nhole) + state |= NHOLE; + if (!lhole && !nhole && xmi_can_merge(left, new)) + state |= NLEFT_CONTIG; + if (!rhole && !nhole && xmi_can_merge(new, right)) + state |= NRIGHT_CONTIG; + if ((state & NBOTH_CONTIG) == NBOTH_CONTIG && + !xmi_can_merge_all(left, new, right)) + state &= ~NRIGHT_CONTIG; + + switch (state & (CLEFT_CONTIG | CRIGHT_CONTIG | CHOLE)) { + case CLEFT_CONTIG | CRIGHT_CONTIG: + /* + * left/curr/right are the same mapping, so deleting curr + * causes 2 new mappings to be created. + */ + ret += 2; + break; + case 0: + /* + * curr is not contiguous with any mapping, so we remove curr + * completely + */ + ret--; + break; + case CHOLE: + /* hole, do nothing */ + break; + case CLEFT_CONTIG: + case CRIGHT_CONTIG: + /* trim either left or right, no change */ + break; + } + + switch (state & (NLEFT_CONTIG | NRIGHT_CONTIG | NHOLE)) { + case NLEFT_CONTIG | NRIGHT_CONTIG: + /* + * left/curr/right will become the same mapping, so adding + * curr causes the deletion of right. + */ + ret--; + break; + case 0: + /* new is not contiguous with any mapping */ + ret++; + break; + case NHOLE: + /* hole, do nothing. */ + break; + case NLEFT_CONTIG: + case NRIGHT_CONTIG: + /* new is absorbed into left or right, no change */ + break; + } + + trace_xfs_exchmaps_delta_nextents_step(mp, left, curr, new, right, ret, + state); + return ret; +} + +/* Make sure we don't overflow the extent (mapping) counters. */ +static inline int +xmi_ensure_delta_nextents( + struct xfs_exchmaps_req *req, + struct xfs_inode *ip, + int64_t delta) +{ + struct xfs_mount *mp = ip->i_mount; + int whichfork = xfs_exchmaps_reqfork(req); + struct xfs_ifork *ifp = xfs_ifork_ptr(ip, whichfork); + uint64_t new_nextents; + xfs_extnum_t max_nextents; + + if (delta < 0) + return 0; + + /* + * It's always an error if the delta causes integer overflow. delta + * needs an explicit cast here to avoid warnings about implicit casts + * coded into the overflow check. + */ + if (check_add_overflow(ifp->if_nextents, (uint64_t)delta, + &new_nextents)) + return -EFBIG; + + if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_REDUCE_MAX_IEXTENTS) && + new_nextents > 10) + return -EFBIG; + + /* + * We always promote both inodes to have large extent counts if the + * superblock feature is enabled, so we only need to check against the + * theoretical maximum. + */ + max_nextents = xfs_iext_max_nextents(xfs_has_large_extent_counts(mp), + whichfork); + if (new_nextents > max_nextents) + return -EFBIG; + + return 0; +} + +/* Find the next mapping after irec. */ +static inline int +xmi_next( + struct xfs_inode *ip, + int bmap_flags, + const struct xfs_bmbt_irec *irec, + struct xfs_bmbt_irec *nrec) +{ + xfs_fileoff_t off; + xfs_filblks_t blockcount; + int nimaps = 1; + int error; + + off = irec->br_startoff + irec->br_blockcount; + blockcount = XFS_MAX_FILEOFF - off; + error = xfs_bmapi_read(ip, off, blockcount, nrec, &nimaps, bmap_flags); + if (error) + return error; + if (nrec->br_startblock == DELAYSTARTBLOCK || + nrec->br_startoff != off) { + /* + * If we don't get the mapping we want, return a zero-length + * mapping, which our estimator function will pretend is a hole. + * We shouldn't get delalloc reservations. + */ + nrec->br_startblock = HOLESTARTBLOCK; + } + + return 0; +} + +int __init +xfs_exchmaps_intent_init_cache(void) +{ + xfs_exchmaps_intent_cache = kmem_cache_create("xfs_exchmaps_intent", + sizeof(struct xfs_exchmaps_intent), + 0, 0, NULL); + + return xfs_exchmaps_intent_cache != NULL ? 0 : -ENOMEM; +} + +void +xfs_exchmaps_intent_destroy_cache(void) +{ + kmem_cache_destroy(xfs_exchmaps_intent_cache); + xfs_exchmaps_intent_cache = NULL; +} + +/* + * Decide if we will exchange the reflink flags between the two files after the + * exchange. The only time we want to do this is if we're exchanging all + * mappings under EOF and the inode reflink flags have different states. + */ +static inline bool +xmi_can_exchange_reflink_flags( + const struct xfs_exchmaps_req *req, + unsigned int reflink_state) +{ + struct xfs_mount *mp = req->ip1->i_mount; + + if (hweight32(reflink_state) != 1) + return false; + if (req->startoff1 != 0 || req->startoff2 != 0) + return false; + if (req->blockcount != XFS_B_TO_FSB(mp, req->ip1->i_disk_size)) + return false; + if (req->blockcount != XFS_B_TO_FSB(mp, req->ip2->i_disk_size)) + return false; + return true; +} + + +/* Allocate and initialize a new incore intent item from a request. */ +struct xfs_exchmaps_intent * +xfs_exchmaps_init_intent( + const struct xfs_exchmaps_req *req) +{ + struct xfs_exchmaps_intent *xmi; + unsigned int rs = 0; + + xmi = kmem_cache_zalloc(xfs_exchmaps_intent_cache, + GFP_NOFS | __GFP_NOFAIL); + INIT_LIST_HEAD(&xmi->xmi_list); + xmi->xmi_ip1 = req->ip1; + xmi->xmi_ip2 = req->ip2; + xmi->xmi_startoff1 = req->startoff1; + xmi->xmi_startoff2 = req->startoff2; + xmi->xmi_blockcount = req->blockcount; + xmi->xmi_isize1 = xmi->xmi_isize2 = -1; + xmi->xmi_flags = req->flags & XFS_EXCHMAPS_PARAMS; + + if (xfs_exchmaps_whichfork(xmi) == XFS_ATTR_FORK) { + xmi->xmi_flags |= __XFS_EXCHMAPS_INO2_SHORTFORM; + return xmi; + } + + if (req->flags & XFS_EXCHMAPS_SET_SIZES) { + xmi->xmi_flags |= XFS_EXCHMAPS_SET_SIZES; + xmi->xmi_isize1 = req->ip2->i_disk_size; + xmi->xmi_isize2 = req->ip1->i_disk_size; + } + + /* Record the state of each inode's reflink flag before the op. */ + if (xfs_is_reflink_inode(req->ip1)) + rs |= 1; + if (xfs_is_reflink_inode(req->ip2)) + rs |= 2; + + /* + * Figure out if we're clearing the reflink flags (which effectively + * exchanges them) after the operation. + */ + if (xmi_can_exchange_reflink_flags(req, rs)) { + if (rs & 1) + xmi->xmi_flags |= XFS_EXCHMAPS_CLEAR_INO1_REFLINK; + if (rs & 2) + xmi->xmi_flags |= XFS_EXCHMAPS_CLEAR_INO2_REFLINK; + } + + if (S_ISDIR(VFS_I(xmi->xmi_ip2)->i_mode) || + S_ISLNK(VFS_I(xmi->xmi_ip2)->i_mode)) + xmi->xmi_flags |= __XFS_EXCHMAPS_INO2_SHORTFORM; + + return xmi; +} + +/* + * Estimate the number of exchange operations and the number of file blocks + * in each file that will be affected by the exchange operation. + */ +int +xfs_exchmaps_estimate( + struct xfs_exchmaps_req *req) +{ + struct xfs_exchmaps_intent *xmi; + struct xfs_bmbt_irec irec1, irec2; + struct xfs_exchmaps_adjacent adj = ADJACENT_INIT; + xfs_filblks_t ip1_blocks = 0, ip2_blocks = 0; + int64_t d_nexts1, d_nexts2; + int bmap_flags; + int error; + + ASSERT(!(req->flags & ~XFS_EXCHMAPS_PARAMS)); + + bmap_flags = xfs_bmapi_aflag(xfs_exchmaps_reqfork(req)); + xmi = xfs_exchmaps_init_intent(req); + + /* + * To guard against the possibility of overflowing the extent counters, + * we have to estimate an upper bound on the potential increase in that + * counter. We can split the mapping at each end of the range, and for + * each step of the exchange we can split the mapping that we're + * working on if the mappings do not align. + */ + d_nexts1 = d_nexts2 = 3; + + while (xmi_has_more_exchange_work(xmi)) { + /* + * Walk through the file ranges until we find something to + * exchange. Because we're simulating the exchange, pass in + * adj to capture skipped mappings for correct estimation of + * bmbt record merges. + */ + error = xfs_exchmaps_find_mappings(xmi, &irec1, &irec2, &adj); + if (error) + goto out_free; + if (!xmi_has_more_exchange_work(xmi)) + break; + + /* Update accounting. */ + if (xfs_bmap_is_real_extent(&irec1)) + ip1_blocks += irec1.br_blockcount; + if (xfs_bmap_is_real_extent(&irec2)) + ip2_blocks += irec2.br_blockcount; + req->nr_exchanges++; + + /* Read the next mappings from both files. */ + error = xmi_next(req->ip1, bmap_flags, &irec1, &adj.right1); + if (error) + goto out_free; + + error = xmi_next(req->ip2, bmap_flags, &irec2, &adj.right2); + if (error) + goto out_free; + + /* Update extent count deltas. */ + d_nexts1 += xmi_delta_nextents_step(req->ip1->i_mount, + &adj.left1, &irec1, &irec2, &adj.right1); + + d_nexts2 += xmi_delta_nextents_step(req->ip1->i_mount, + &adj.left2, &irec2, &irec1, &adj.right2); + + /* Now pretend we exchanged the mappings. */ + if (xmi_can_merge(&adj.left2, &irec1)) + adj.left2.br_blockcount += irec1.br_blockcount; + else + memcpy(&adj.left2, &irec1, sizeof(irec1)); + + if (xmi_can_merge(&adj.left1, &irec2)) + adj.left1.br_blockcount += irec2.br_blockcount; + else + memcpy(&adj.left1, &irec2, sizeof(irec2)); + + xmi_advance(xmi, &irec1); + } + + /* Account for the blocks that are being exchanged. */ + if (XFS_IS_REALTIME_INODE(req->ip1) && + xfs_exchmaps_reqfork(req) == XFS_DATA_FORK) { + req->ip1_rtbcount = ip1_blocks; + req->ip2_rtbcount = ip2_blocks; + } else { + req->ip1_bcount = ip1_blocks; + req->ip2_bcount = ip2_blocks; + } + + /* + * Make sure that both forks have enough slack left in their extent + * counters that the exchange operation will not overflow. + */ + trace_xfs_exchmaps_delta_nextents(req, d_nexts1, d_nexts2); + if (req->ip1 == req->ip2) { + error = xmi_ensure_delta_nextents(req, req->ip1, + d_nexts1 + d_nexts2); + } else { + error = xmi_ensure_delta_nextents(req, req->ip1, d_nexts1); + if (error) + goto out_free; + error = xmi_ensure_delta_nextents(req, req->ip2, d_nexts2); + } + if (error) + goto out_free; + + trace_xfs_exchmaps_initial_estimate(req); + error = xfs_exchmaps_estimate_overhead(req); +out_free: + kmem_cache_free(xfs_exchmaps_intent_cache, xmi); + return error; +} + +/* Set the reflink flag before an operation. */ +static inline void +xfs_exchmaps_set_reflink( + struct xfs_trans *tp, + struct xfs_inode *ip) +{ + trace_xfs_reflink_set_inode_flag(ip); + + ip->i_diflags2 |= XFS_DIFLAG2_REFLINK; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); +} + +/* + * If either file has shared blocks and we're exchanging data forks, we must + * flag the other file as having shared blocks so that we get the shared-block + * rmap functions if we need to fix up the rmaps. + */ +void +xfs_exchmaps_ensure_reflink( + struct xfs_trans *tp, + const struct xfs_exchmaps_intent *xmi) +{ + unsigned int rs = 0; + + if (xfs_is_reflink_inode(xmi->xmi_ip1)) + rs |= 1; + if (xfs_is_reflink_inode(xmi->xmi_ip2)) + rs |= 2; + + if ((rs & 1) && !xfs_is_reflink_inode(xmi->xmi_ip2)) + xfs_exchmaps_set_reflink(tp, xmi->xmi_ip2); + + if ((rs & 2) && !xfs_is_reflink_inode(xmi->xmi_ip1)) + xfs_exchmaps_set_reflink(tp, xmi->xmi_ip1); +} + +/* Set the large extent count flag before an operation if needed. */ +static inline void +xfs_exchmaps_ensure_large_extent_counts( + struct xfs_trans *tp, + struct xfs_inode *ip) +{ + if (xfs_inode_has_large_extent_counts(ip)) + return; + + ip->i_diflags2 |= XFS_DIFLAG2_NREXT64; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); +} + +/* Widen the extent counter fields of both inodes if necessary. */ +void +xfs_exchmaps_upgrade_extent_counts( + struct xfs_trans *tp, + const struct xfs_exchmaps_intent *xmi) +{ + if (!xfs_has_large_extent_counts(tp->t_mountp)) + return; + + xfs_exchmaps_ensure_large_extent_counts(tp, xmi->xmi_ip1); + xfs_exchmaps_ensure_large_extent_counts(tp, xmi->xmi_ip2); +} + +/* + * Schedule an exchange a range of mappings from one inode to another. + * + * The use of file mapping exchange log intent items ensures the operation can + * be resumed even if the system goes down. The caller must commit the + * transaction to start the work. + * + * The caller must ensure the inodes must be joined to the transaction and + * ILOCKd; they will still be joined to the transaction at exit. + */ +void +xfs_exchange_mappings( + struct xfs_trans *tp, + const struct xfs_exchmaps_req *req) +{ + struct xfs_exchmaps_intent *xmi; + + BUILD_BUG_ON(XFS_EXCHMAPS_INTERNAL_FLAGS & XFS_EXCHMAPS_LOGGED_FLAGS); + + xfs_assert_ilocked(req->ip1, XFS_ILOCK_EXCL); + xfs_assert_ilocked(req->ip2, XFS_ILOCK_EXCL); + ASSERT(!(req->flags & ~XFS_EXCHMAPS_LOGGED_FLAGS)); + if (req->flags & XFS_EXCHMAPS_SET_SIZES) + ASSERT(!(req->flags & XFS_EXCHMAPS_ATTR_FORK)); + ASSERT(xfs_has_exchange_range(tp->t_mountp)); + + if (req->blockcount == 0) + return; + + xmi = xfs_exchmaps_init_intent(req); + xfs_exchmaps_defer_add(tp, xmi); + xfs_exchmaps_ensure_reflink(tp, xmi); + xfs_exchmaps_upgrade_extent_counts(tp, xmi); +} |