LXR linux/fs/ext4/fsync.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/ext4/fsync.c
   4 *
   5 *  Copyright (C) 1993  Stephen Tweedie (sct@redhat.com)
   6 *  from
   7 *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
   8 *                      Laboratoire MASI - Institut Blaise Pascal
   9 *                      Universite Pierre et Marie Curie (Paris VI)
  10 *  from
  11 *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
  12 *
  13 *  ext4fs fsync primitive
  14 *
  15 *  Big-endian to little-endian byte-swapping/bitmaps by
  16 *        David S. Miller (davem@caip.rutgers.edu), 1995
  17 *
  18 *  Removed unnecessary code duplication for little endian machines
  19 *  and excessive __inline__s.
  20 *        Andi Kleen, 1997
  21 *
  22 * Major simplications and cleanup - we only need to do the metadata, because
  23 * we can depend on generic_block_fdatasync() to sync the data blocks.
  24 */
  25
  26#include <linux/time.h>
  27#include <linux/fs.h>
  28#include <linux/sched.h>
  29#include <linux/writeback.h>
  30#include <linux/blkdev.h>
  31
  32#include "ext4.h"
  33#include "ext4_jbd2.h"
  34
  35#include <trace/events/ext4.h>
  36
  37/*
  38 * If we're not journaling and this is a just-created file, we have to
  39 * sync our parent directory (if it was freshly created) since
  40 * otherwise it will only be written by writeback, leaving a huge
  41 * window during which a crash may lose the file.  This may apply for
  42 * the parent directory's parent as well, and so on recursively, if
  43 * they are also freshly created.
  44 */
  45static int ext4_sync_parent(struct inode *inode)
  46{
  47        struct dentry *dentry = NULL;
  48        struct inode *next;
  49        int ret = 0;
  50
  51        if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
  52                return 0;
  53        inode = igrab(inode);
  54        while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
  55                ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
  56                dentry = d_find_any_alias(inode);
  57                if (!dentry)
  58                        break;
  59                next = igrab(d_inode(dentry->d_parent));
  60                dput(dentry);
  61                if (!next)
  62                        break;
  63                iput(inode);
  64                inode = next;
  65                /*
  66                 * The directory inode may have gone through rmdir by now. But
  67                 * the inode itself and its blocks are still allocated (we hold
  68                 * a reference to the inode so it didn't go through
  69                 * ext4_evict_inode()) and so we are safe to flush metadata
  70                 * blocks and the inode.
  71                 */
  72                ret = sync_mapping_buffers(inode->i_mapping);
  73                if (ret)
  74                        break;
  75                ret = sync_inode_metadata(inode, 1);
  76                if (ret)
  77                        break;
  78        }
  79        iput(inode);
  80        return ret;
  81}
  82
  83/*
  84 * akpm: A new design for ext4_sync_file().
  85 *
  86 * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
  87 * There cannot be a transaction open by this task.
  88 * Another task could have dirtied this inode.  Its data can be in any
  89 * state in the journalling system.
  90 *
  91 * What we do is just kick off a commit and wait on it.  This will snapshot the
  92 * inode to disk.
  93 */
  94
  95int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
  96{
  97        struct inode *inode = file->f_mapping->host;
  98        struct ext4_inode_info *ei = EXT4_I(inode);
  99        journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
 100        int ret = 0, err;
 101        tid_t commit_tid;
 102        bool needs_barrier = false;
 103
 104        if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 105                return -EIO;
 106
 107        J_ASSERT(ext4_journal_current_handle() == NULL);
 108
 109        trace_ext4_sync_file_enter(file, datasync);
 110
 111        if (sb_rdonly(inode->i_sb)) {
 112                /* Make sure that we read updated s_mount_flags value */
 113                smp_rmb();
 114                if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
 115                        ret = -EROFS;
 116                goto out;
 117        }
 118
 119        if (!journal) {
 120                ret = __generic_file_fsync(file, start, end, datasync);
 121                if (!ret)
 122                        ret = ext4_sync_parent(inode);
 123                if (test_opt(inode->i_sb, BARRIER))
 124                        goto issue_flush;
 125                goto out;
 126        }
 127
 128        ret = file_write_and_wait_range(file, start, end);
 129        if (ret)
 130                return ret;
 131        /*
 132         * data=writeback,ordered:
 133         *  The caller's filemap_fdatawrite()/wait will sync the data.
 134         *  Metadata is in the journal, we wait for proper transaction to
 135         *  commit here.
 136         *
 137         * data=journal:
 138         *  filemap_fdatawrite won't do anything (the buffers are clean).
 139         *  ext4_force_commit will write the file data into the journal and
 140         *  will wait on that.
 141         *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
 142         *  (they were dirtied by commit).  But that's OK - the blocks are
 143         *  safe in-journal, which is all fsync() needs to ensure.
 144         */
 145        if (ext4_should_journal_data(inode)) {
 146                ret = ext4_force_commit(inode->i_sb);
 147                goto out;
 148        }
 149
 150        commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
 151        if (journal->j_flags & JBD2_BARRIER &&
 152            !jbd2_trans_will_send_data_barrier(journal, commit_tid))
 153                needs_barrier = true;
 154        ret = jbd2_complete_transaction(journal, commit_tid);
 155        if (needs_barrier) {
 156        issue_flush:
 157                err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
 158                if (!ret)
 159                        ret = err;
 160        }
 161out:
 162        trace_ext4_sync_file_exit(inode, ret);
 163        return ret;
 164}
 165