diff options
Diffstat (limited to 'fs/xfs/xfs_iomap.c')
| -rw-r--r-- | fs/xfs/xfs_iomap.c | 920 |
1 files changed, 920 insertions, 0 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c new file mode 100644 index 000000000..38e633bad --- /dev/null +++ b/fs/xfs/xfs_iomap.c @@ -0,0 +1,920 @@ +/* + * Copyright (c) 2000-2006 Silicon Graphics, Inc. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ +#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_inode.h" +#include "xfs_btree.h" +#include "xfs_bmap_btree.h" +#include "xfs_bmap.h" +#include "xfs_bmap_util.h" +#include "xfs_error.h" +#include "xfs_trans.h" +#include "xfs_trans_space.h" +#include "xfs_iomap.h" +#include "xfs_trace.h" +#include "xfs_icache.h" +#include "xfs_quota.h" +#include "xfs_dquot_item.h" +#include "xfs_dquot.h" + + +#define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \ + << mp->m_writeio_log) +#define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP + +STATIC int +xfs_iomap_eof_align_last_fsb( + xfs_mount_t *mp, + xfs_inode_t *ip, + xfs_extlen_t extsize, + xfs_fileoff_t *last_fsb) +{ + xfs_extlen_t align = 0; + int eof, error; + + if (!XFS_IS_REALTIME_INODE(ip)) { + /* + * Round up the allocation request to a stripe unit + * (m_dalign) boundary if the file size is >= stripe unit + * size, and we are allocating past the allocation eof. + * + * If mounted with the "-o swalloc" option the alignment is + * increased from the strip unit size to the stripe width. + */ + if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC)) + align = mp->m_swidth; + else if (mp->m_dalign) + align = mp->m_dalign; + + if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align)) + align = 0; + } + + /* + * Always round up the allocation request to an extent boundary + * (when file on a real-time subvolume or has di_extsize hint). + */ + if (extsize) { + if (align) + align = roundup_64(align, extsize); + else + align = extsize; + } + + if (align) { + xfs_fileoff_t new_last_fsb = roundup_64(*last_fsb, align); + error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof); + if (error) + return error; + if (eof) + *last_fsb = new_last_fsb; + } + return 0; +} + +STATIC int +xfs_alert_fsblock_zero( + xfs_inode_t *ip, + xfs_bmbt_irec_t *imap) +{ + xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO, + "Access to block zero in inode %llu " + "start_block: %llx start_off: %llx " + "blkcnt: %llx extent-state: %x", + (unsigned long long)ip->i_ino, + (unsigned long long)imap->br_startblock, + (unsigned long long)imap->br_startoff, + (unsigned long long)imap->br_blockcount, + imap->br_state); + return -EFSCORRUPTED; +} + +int +xfs_iomap_write_direct( + xfs_inode_t *ip, + xfs_off_t offset, + size_t count, + xfs_bmbt_irec_t *imap, + int nmaps) +{ + xfs_mount_t *mp = ip->i_mount; + xfs_fileoff_t offset_fsb; + xfs_fileoff_t last_fsb; + xfs_filblks_t count_fsb, resaligned; + xfs_fsblock_t firstfsb; + xfs_extlen_t extsz, temp; + int nimaps; + int quota_flag; + int rt; + xfs_trans_t *tp; + xfs_bmap_free_t free_list; + uint qblocks, resblks, resrtextents; + int committed; + int error; + + error = xfs_qm_dqattach(ip, 0); + if (error) + return error; + + rt = XFS_IS_REALTIME_INODE(ip); + extsz = xfs_get_extsz_hint(ip); + + offset_fsb = XFS_B_TO_FSBT(mp, offset); + last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count))); + if ((offset + count) > XFS_ISIZE(ip)) { + error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb); + if (error) + return error; + } else { + if (nmaps && (imap->br_startblock == HOLESTARTBLOCK)) + last_fsb = MIN(last_fsb, (xfs_fileoff_t) + imap->br_blockcount + + imap->br_startoff); + } + count_fsb = last_fsb - offset_fsb; + ASSERT(count_fsb > 0); + + resaligned = count_fsb; + if (unlikely(extsz)) { + if ((temp = do_mod(offset_fsb, extsz))) + resaligned += temp; + if ((temp = do_mod(resaligned, extsz))) + resaligned += extsz - temp; + } + + if (unlikely(rt)) { + resrtextents = qblocks = resaligned; + resrtextents /= mp->m_sb.sb_rextsize; + resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); + quota_flag = XFS_QMOPT_RES_RTBLKS; + } else { + resrtextents = 0; + resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned); + quota_flag = XFS_QMOPT_RES_REGBLKS; + } + + /* + * Allocate and setup the transaction + */ + tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT); + error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, + resblks, resrtextents); + /* + * Check for running out of space, note: need lock to return + */ + if (error) { + xfs_trans_cancel(tp, 0); + return error; + } + + xfs_ilock(ip, XFS_ILOCK_EXCL); + + error = xfs_trans_reserve_quota_nblks(tp, ip, qblocks, 0, quota_flag); + if (error) + goto out_trans_cancel; + + xfs_trans_ijoin(tp, ip, 0); + + /* + * From this point onwards we overwrite the imap pointer that the + * caller gave to us. + */ + xfs_bmap_init(&free_list, &firstfsb); + nimaps = 1; + error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, + XFS_BMAPI_PREALLOC, &firstfsb, 0, + imap, &nimaps, &free_list); + if (error) + goto out_bmap_cancel; + + /* + * Complete the transaction + */ + error = xfs_bmap_finish(&tp, &free_list, &committed); + if (error) + goto out_bmap_cancel; + error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); + if (error) + goto out_unlock; + + /* + * Copy any maps to caller's array and return any error. + */ + if (nimaps == 0) { + error = -ENOSPC; + goto out_unlock; + } + + if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) + error = xfs_alert_fsblock_zero(ip, imap); + +out_unlock: + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; + +out_bmap_cancel: + xfs_bmap_cancel(&free_list); + xfs_trans_unreserve_quota_nblks(tp, ip, (long)qblocks, 0, quota_flag); +out_trans_cancel: + xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT); + goto out_unlock; +} + +/* + * If the caller is doing a write at the end of the file, then extend the + * allocation out to the file system's write iosize. We clean up any extra + * space left over when the file is closed in xfs_inactive(). + * + * If we find we already have delalloc preallocation beyond EOF, don't do more + * preallocation as it it not needed. + */ +STATIC int +xfs_iomap_eof_want_preallocate( + xfs_mount_t *mp, + xfs_inode_t *ip, + xfs_off_t offset, + size_t count, + xfs_bmbt_irec_t *imap, + int nimaps, + int *prealloc) +{ + xfs_fileoff_t start_fsb; + xfs_filblks_t count_fsb; + int n, error, imaps; + int found_delalloc = 0; + + *prealloc = 0; + if (offset + count <= XFS_ISIZE(ip)) + return 0; + + /* + * If the file is smaller than the minimum prealloc and we are using + * dynamic preallocation, don't do any preallocation at all as it is + * likely this is the only write to the file that is going to be done. + */ + if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) && + XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks)) + return 0; + + /* + * If there are any real blocks past eof, then don't + * do any speculative allocation. + */ + start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1))); + count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes); + while (count_fsb > 0) { + imaps = nimaps; + error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps, + 0); + if (error) + return error; + for (n = 0; n < imaps; n++) { + if ((imap[n].br_startblock != HOLESTARTBLOCK) && + (imap[n].br_startblock != DELAYSTARTBLOCK)) + return 0; + start_fsb += imap[n].br_blockcount; + count_fsb -= imap[n].br_blockcount; + + if (imap[n].br_startblock == DELAYSTARTBLOCK) + found_delalloc = 1; + } + } + if (!found_delalloc) + *prealloc = 1; + return 0; +} + +/* + * Determine the initial size of the preallocation. We are beyond the current + * EOF here, but we need to take into account whether this is a sparse write or + * an extending write when determining the preallocation size. Hence we need to + * look up the extent that ends at the current write offset and use the result + * to determine the preallocation size. + * + * If the extent is a hole, then preallocation is essentially disabled. + * Otherwise we take the size of the preceeding data extent as the basis for the + * preallocation size. If the size of the extent is greater than half the + * maximum extent length, then use the current offset as the basis. This ensures + * that for large files the preallocation size always extends to MAXEXTLEN + * rather than falling short due to things like stripe unit/width alignment of + * real extents. + */ +STATIC xfs_fsblock_t +xfs_iomap_eof_prealloc_initial_size( + struct xfs_mount *mp, + struct xfs_inode *ip, + xfs_off_t offset, + xfs_bmbt_irec_t *imap, + int nimaps) +{ + xfs_fileoff_t start_fsb; + int imaps = 1; + int error; + + ASSERT(nimaps >= imaps); + + /* if we are using a specific prealloc size, return now */ + if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) + return 0; + + /* If the file is small, then use the minimum prealloc */ + if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign)) + return 0; + + /* + * As we write multiple pages, the offset will always align to the + * start of a page and hence point to a hole at EOF. i.e. if the size is + * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096) + * will return FSB 1. Hence if there are blocks in the file, we want to + * point to the block prior to the EOF block and not the hole that maps + * directly at @offset. + */ + start_fsb = XFS_B_TO_FSB(mp, offset); + if (start_fsb) + start_fsb--; + error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE); + if (error) + return 0; + + ASSERT(imaps == 1); + if (imap[0].br_startblock == HOLESTARTBLOCK) + return 0; + if (imap[0].br_blockcount <= (MAXEXTLEN >> 1)) + return imap[0].br_blockcount << 1; + return XFS_B_TO_FSB(mp, offset); +} + +STATIC bool +xfs_quota_need_throttle( + struct xfs_inode *ip, + int type, + xfs_fsblock_t alloc_blocks) +{ + struct xfs_dquot *dq = xfs_inode_dquot(ip, type); + + if (!dq || !xfs_this_quota_on(ip->i_mount, type)) + return false; + + /* no hi watermark, no throttle */ + if (!dq->q_prealloc_hi_wmark) + return false; + + /* under the lo watermark, no throttle */ + if (dq->q_res_bcount + alloc_blocks < dq->q_prealloc_lo_wmark) + return false; + + return true; +} + +STATIC void +xfs_quota_calc_throttle( + struct xfs_inode *ip, + int type, + xfs_fsblock_t *qblocks, + int *qshift, + int64_t *qfreesp) +{ + int64_t freesp; + int shift = 0; + struct xfs_dquot *dq = xfs_inode_dquot(ip, type); + + /* no dq, or over hi wmark, squash the prealloc completely */ + if (!dq || dq->q_res_bcount >= dq->q_prealloc_hi_wmark) { + *qblocks = 0; + *qfreesp = 0; + return; + } + + freesp = dq->q_prealloc_hi_wmark - dq->q_res_bcount; + if (freesp < dq->q_low_space[XFS_QLOWSP_5_PCNT]) { + shift = 2; + if (freesp < dq->q_low_space[XFS_QLOWSP_3_PCNT]) + shift += 2; + if (freesp < dq->q_low_space[XFS_QLOWSP_1_PCNT]) + shift += 2; + } + + if (freesp < *qfreesp) + *qfreesp = freesp; + + /* only overwrite the throttle values if we are more aggressive */ + if ((freesp >> shift) < (*qblocks >> *qshift)) { + *qblocks = freesp; + *qshift = shift; + } +} + +/* + * If we don't have a user specified preallocation size, dynamically increase + * the preallocation size as the size of the file grows. Cap the maximum size + * at a single extent or less if the filesystem is near full. The closer the + * filesystem is to full, the smaller the maximum prealocation. + */ +STATIC xfs_fsblock_t +xfs_iomap_prealloc_size( + struct xfs_mount *mp, + struct xfs_inode *ip, + xfs_off_t offset, + struct xfs_bmbt_irec *imap, + int nimaps) +{ + xfs_fsblock_t alloc_blocks = 0; + int shift = 0; + int64_t freesp; + xfs_fsblock_t qblocks; + int qshift = 0; + + alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset, + imap, nimaps); + if (!alloc_blocks) + goto check_writeio; + qblocks = alloc_blocks; + + /* + * MAXEXTLEN is not a power of two value but we round the prealloc down + * to the nearest power of two value after throttling. To prevent the + * round down from unconditionally reducing the maximum supported prealloc + * size, we round up first, apply appropriate throttling, round down and + * cap the value to MAXEXTLEN. + */ + alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), + alloc_blocks); + + freesp = percpu_counter_read_positive(&mp->m_fdblocks); + if (freesp < mp->m_low_space[XFS_LOWSP_5_PCNT]) { + shift = 2; + if (freesp < mp->m_low_space[XFS_LOWSP_4_PCNT]) + shift++; + if (freesp < mp->m_low_space[XFS_LOWSP_3_PCNT]) + shift++; + if (freesp < mp->m_low_space[XFS_LOWSP_2_PCNT]) + shift++; + if (freesp < mp->m_low_space[XFS_LOWSP_1_PCNT]) + shift++; + } + + /* + * Check each quota to cap the prealloc size, provide a shift value to + * throttle with and adjust amount of available space. + */ + if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks)) + xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift, + &freesp); + if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks)) + xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift, + &freesp); + if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks)) + xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift, + &freesp); + + /* + * The final prealloc size is set to the minimum of free space available + * in each of the quotas and the overall filesystem. + * + * The shift throttle value is set to the maximum value as determined by + * the global low free space values and per-quota low free space values. + */ + alloc_blocks = MIN(alloc_blocks, qblocks); + shift = MAX(shift, qshift); + + if (shift) + alloc_blocks >>= shift; + /* + * rounddown_pow_of_two() returns an undefined result if we pass in + * alloc_blocks = 0. + */ + if (alloc_blocks) + alloc_blocks = rounddown_pow_of_two(alloc_blocks); + if (alloc_blocks > MAXEXTLEN) + alloc_blocks = MAXEXTLEN; + + /* + * If we are still trying to allocate more space than is + * available, squash the prealloc hard. This can happen if we + * have a large file on a small filesystem and the above + * lowspace thresholds are smaller than MAXEXTLEN. + */ + while (alloc_blocks && alloc_blocks >= freesp) + alloc_blocks >>= 4; + +check_writeio: + if (alloc_blocks < mp->m_writeio_blocks) + alloc_blocks = mp->m_writeio_blocks; + + trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift, + mp->m_writeio_blocks); + + return alloc_blocks; +} + +int +xfs_iomap_write_delay( + xfs_inode_t *ip, + xfs_off_t offset, + size_t count, + xfs_bmbt_irec_t *ret_imap) +{ + xfs_mount_t *mp = ip->i_mount; + xfs_fileoff_t offset_fsb; + xfs_fileoff_t last_fsb; + xfs_off_t aligned_offset; + xfs_fileoff_t ioalign; + xfs_extlen_t extsz; + int nimaps; + xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS]; + int prealloc; + int error; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); + + /* + * Make sure that the dquots are there. This doesn't hold + * the ilock across a disk read. + */ + error = xfs_qm_dqattach_locked(ip, 0); + if (error) + return error; + + extsz = xfs_get_extsz_hint(ip); + offset_fsb = XFS_B_TO_FSBT(mp, offset); + + error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count, + imap, XFS_WRITE_IMAPS, &prealloc); + if (error) + return error; + +retry: + if (prealloc) { + xfs_fsblock_t alloc_blocks; + + alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap, + XFS_WRITE_IMAPS); + + aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1)); + ioalign = XFS_B_TO_FSBT(mp, aligned_offset); + last_fsb = ioalign + alloc_blocks; + } else { + last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count))); + } + + if (prealloc || extsz) { + error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb); + if (error) + return error; + } + + /* + * Make sure preallocation does not create extents beyond the range we + * actually support in this filesystem. + */ + if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes)) + last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes); + + ASSERT(last_fsb > offset_fsb); + + nimaps = XFS_WRITE_IMAPS; + error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb, + imap, &nimaps, XFS_BMAPI_ENTIRE); + switch (error) { + case 0: + case -ENOSPC: + case -EDQUOT: + break; + default: + return error; + } + + /* + * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry + * without EOF preallocation. + */ + if (nimaps == 0) { + trace_xfs_delalloc_enospc(ip, offset, count); + if (prealloc) { + prealloc = 0; + error = 0; + goto retry; + } + return error ? error : -ENOSPC; + } + + if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip))) + return xfs_alert_fsblock_zero(ip, &imap[0]); + + /* + * Tag the inode as speculatively preallocated so we can reclaim this + * space on demand, if necessary. + */ + if (prealloc) + xfs_inode_set_eofblocks_tag(ip); + + *ret_imap = imap[0]; + return 0; +} + +/* + * Pass in a delayed allocate extent, convert it to real extents; + * return to the caller the extent we create which maps on top of + * the originating callers request. + * + * Called without a lock on the inode. + * + * We no longer bother to look at the incoming map - all we have to + * guarantee is that whatever we allocate fills the required range. + */ +int +xfs_iomap_write_allocate( + xfs_inode_t *ip, + xfs_off_t offset, + xfs_bmbt_irec_t *imap) +{ + xfs_mount_t *mp = ip->i_mount; + xfs_fileoff_t offset_fsb, last_block; + xfs_fileoff_t end_fsb, map_start_fsb; + xfs_fsblock_t first_block; + xfs_bmap_free_t free_list; + xfs_filblks_t count_fsb; + xfs_trans_t *tp; + int nimaps, committed; + int error = 0; + int nres; + + /* + * Make sure that the dquots are there. + */ + error = xfs_qm_dqattach(ip, 0); + if (error) + return error; + + offset_fsb = XFS_B_TO_FSBT(mp, offset); + count_fsb = imap->br_blockcount; + map_start_fsb = imap->br_startoff; + + XFS_STATS_ADD(xs_xstrat_bytes, XFS_FSB_TO_B(mp, count_fsb)); + + while (count_fsb != 0) { + /* + * Set up a transaction with which to allocate the + * backing store for the file. Do allocations in a + * loop until we get some space in the range we are + * interested in. The other space that might be allocated + * is in the delayed allocation extent on which we sit + * but before our buffer starts. + */ + + nimaps = 0; + while (nimaps == 0) { + tp = xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE); + tp->t_flags |= XFS_TRANS_RESERVE; + nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK); + error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, + nres, 0); + if (error) { + xfs_trans_cancel(tp, 0); + return error; + } + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + xfs_bmap_init(&free_list, &first_block); + + /* + * it is possible that the extents have changed since + * we did the read call as we dropped the ilock for a + * while. We have to be careful about truncates or hole + * punchs here - we are not allowed to allocate + * non-delalloc blocks here. + * + * The only protection against truncation is the pages + * for the range we are being asked to convert are + * locked and hence a truncate will block on them + * first. + * + * As a result, if we go beyond the range we really + * need and hit an delalloc extent boundary followed by + * a hole while we have excess blocks in the map, we + * will fill the hole incorrectly and overrun the + * transaction reservation. + * + * Using a single map prevents this as we are forced to + * check each map we look for overlap with the desired + * range and abort as soon as we find it. Also, given + * that we only return a single map, having one beyond + * what we can return is probably a bit silly. + * + * We also need to check that we don't go beyond EOF; + * this is a truncate optimisation as a truncate sets + * the new file size before block on the pages we + * currently have locked under writeback. Because they + * are about to be tossed, we don't need to write them + * back.... + */ + nimaps = 1; + end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip)); + error = xfs_bmap_last_offset(ip, &last_block, + XFS_DATA_FORK); + if (error) + goto trans_cancel; + + last_block = XFS_FILEOFF_MAX(last_block, end_fsb); + if ((map_start_fsb + count_fsb) > last_block) { + count_fsb = last_block - map_start_fsb; + if (count_fsb == 0) { + error = -EAGAIN; + goto trans_cancel; + } + } + + /* + * From this point onwards we overwrite the imap + * pointer that the caller gave to us. + */ + error = xfs_bmapi_write(tp, ip, map_start_fsb, + count_fsb, 0, + &first_block, 1, + imap, &nimaps, &free_list); + if (error) + goto trans_cancel; + + error = xfs_bmap_finish(&tp, &free_list, &committed); + if (error) + goto trans_cancel; + + error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); + if (error) + goto error0; + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + } + + /* + * See if we were able to allocate an extent that + * covers at least part of the callers request + */ + if (!(imap->br_startblock || XFS_IS_REALTIME_INODE(ip))) + return xfs_alert_fsblock_zero(ip, imap); + + if ((offset_fsb >= imap->br_startoff) && + (offset_fsb < (imap->br_startoff + + imap->br_blockcount))) { + XFS_STATS_INC(xs_xstrat_quick); + return 0; + } + + /* + * So far we have not mapped the requested part of the + * file, just surrounding data, try again. + */ + count_fsb -= imap->br_blockcount; + map_start_fsb = imap->br_startoff + imap->br_blockcount; + } + +trans_cancel: + xfs_bmap_cancel(&free_list); + xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT); +error0: + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +} + +int +xfs_iomap_write_unwritten( + xfs_inode_t *ip, + xfs_off_t offset, + xfs_off_t count) +{ + xfs_mount_t *mp = ip->i_mount; + xfs_fileoff_t offset_fsb; + xfs_filblks_t count_fsb; + xfs_filblks_t numblks_fsb; + xfs_fsblock_t firstfsb; + int nimaps; + xfs_trans_t *tp; + xfs_bmbt_irec_t imap; + xfs_bmap_free_t free_list; + xfs_fsize_t i_size; + uint resblks; + int committed; + int error; + + trace_xfs_unwritten_convert(ip, offset, count); + + offset_fsb = XFS_B_TO_FSBT(mp, offset); + count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count); + count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb); + + /* + * Reserve enough blocks in this transaction for two complete extent + * btree splits. We may be converting the middle part of an unwritten + * extent and in this case we will insert two new extents in the btree + * each of which could cause a full split. + * + * This reservation amount will be used in the first call to + * xfs_bmbt_split() to select an AG with enough space to satisfy the + * rest of the operation. + */ + resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1; + + do { + /* + * set up a transaction to convert the range of extents + * from unwritten to real. Do allocations in a loop until + * we have covered the range passed in. + * + * Note that we open code the transaction allocation here + * to pass KM_NOFS--we can't risk to recursing back into + * the filesystem here as we might be asked to write out + * the same inode that we complete here and might deadlock + * on the iolock. + */ + sb_start_intwrite(mp->m_super); + tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS); + tp->t_flags |= XFS_TRANS_RESERVE | XFS_TRANS_FREEZE_PROT; + error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write, + resblks, 0); + if (error) { + xfs_trans_cancel(tp, 0); + return error; + } + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* + * Modify the unwritten extent state of the buffer. + */ + xfs_bmap_init(&free_list, &firstfsb); + nimaps = 1; + error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, + XFS_BMAPI_CONVERT, &firstfsb, + 1, &imap, &nimaps, &free_list); + if (error) + goto error_on_bmapi_transaction; + + /* + * Log the updated inode size as we go. We have to be careful + * to only log it up to the actual write offset if it is + * halfway into a block. + */ + i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb); + if (i_size > offset + count) + i_size = offset + count; + + i_size = xfs_new_eof(ip, i_size); + if (i_size) { + ip->i_d.di_size = i_size; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); + } + + error = xfs_bmap_finish(&tp, &free_list, &committed); + if (error) + goto error_on_bmapi_transaction; + + error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + if (error) + return error; + + if (!(imap.br_startblock || XFS_IS_REALTIME_INODE(ip))) + return xfs_alert_fsblock_zero(ip, &imap); + + if ((numblks_fsb = imap.br_blockcount) == 0) { + /* + * The numblks_fsb value should always get + * smaller, otherwise the loop is stuck. + */ + ASSERT(imap.br_blockcount); + break; + } + offset_fsb += numblks_fsb; + count_fsb -= numblks_fsb; + } while (count_fsb > 0); + + return 0; + +error_on_bmapi_transaction: + xfs_bmap_cancel(&free_list); + xfs_trans_cancel(tp, (XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT)); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +} |