--- /dev/null
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff