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       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                 :            :  */
      45                 :          0 : static int ext4_sync_parent(struct inode *inode)
      46                 :            : {
      47                 :          0 :         struct dentry *dentry = NULL;
      48                 :          0 :         struct inode *next;
      49                 :          0 :         int ret = 0;
      50                 :            : 
      51         [ #  # ]:          0 :         if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
      52                 :            :                 return 0;
      53                 :          0 :         inode = igrab(inode);
      54         [ #  # ]:          0 :         while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
      55                 :          0 :                 ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
      56                 :          0 :                 dentry = d_find_any_alias(inode);
      57         [ #  # ]:          0 :                 if (!dentry)
      58                 :            :                         break;
      59                 :          0 :                 next = igrab(d_inode(dentry->d_parent));
      60                 :          0 :                 dput(dentry);
      61         [ #  # ]:          0 :                 if (!next)
      62                 :            :                         break;
      63                 :          0 :                 iput(inode);
      64                 :          0 :                 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                 :          0 :                 ret = sync_mapping_buffers(inode->i_mapping);
      73         [ #  # ]:          0 :                 if (ret)
      74                 :            :                         break;
      75                 :          0 :                 ret = sync_inode_metadata(inode, 1);
      76         [ #  # ]:          0 :                 if (ret)
      77                 :            :                         break;
      78                 :            :         }
      79                 :          0 :         iput(inode);
      80                 :          0 :         return ret;
      81                 :            : }
      82                 :            : 
      83                 :          0 : static int ext4_fsync_nojournal(struct inode *inode, bool datasync,
      84                 :            :                                 bool *needs_barrier)
      85                 :            : {
      86                 :          0 :         int ret, err;
      87                 :            : 
      88                 :          0 :         ret = sync_mapping_buffers(inode->i_mapping);
      89         [ #  # ]:          0 :         if (!(inode->i_state & I_DIRTY_ALL))
      90                 :            :                 return ret;
      91   [ #  #  #  # ]:          0 :         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
      92                 :            :                 return ret;
      93                 :            : 
      94                 :          0 :         err = sync_inode_metadata(inode, 1);
      95         [ #  # ]:          0 :         if (!ret)
      96                 :          0 :                 ret = err;
      97                 :            : 
      98         [ #  # ]:          0 :         if (!ret)
      99                 :          0 :                 ret = ext4_sync_parent(inode);
     100         [ #  # ]:          0 :         if (test_opt(inode->i_sb, BARRIER))
     101                 :          0 :                 *needs_barrier = true;
     102                 :            : 
     103                 :            :         return ret;
     104                 :            : }
     105                 :            : 
     106                 :         21 : static int ext4_fsync_journal(struct inode *inode, bool datasync,
     107                 :            :                              bool *needs_barrier)
     108                 :            : {
     109                 :         21 :         struct ext4_inode_info *ei = EXT4_I(inode);
     110         [ -  + ]:         21 :         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
     111         [ -  + ]:         21 :         tid_t commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
     112                 :            : 
     113   [ +  -  -  + ]:         42 :         if (journal->j_flags & JBD2_BARRIER &&
     114                 :         21 :             !jbd2_trans_will_send_data_barrier(journal, commit_tid))
     115                 :          0 :                 *needs_barrier = true;
     116                 :            : 
     117                 :         21 :         return jbd2_complete_transaction(journal, commit_tid);
     118                 :            : }
     119                 :            : 
     120                 :            : /*
     121                 :            :  * akpm: A new design for ext4_sync_file().
     122                 :            :  *
     123                 :            :  * This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
     124                 :            :  * There cannot be a transaction open by this task.
     125                 :            :  * Another task could have dirtied this inode.  Its data can be in any
     126                 :            :  * state in the journalling system.
     127                 :            :  *
     128                 :            :  * What we do is just kick off a commit and wait on it.  This will snapshot the
     129                 :            :  * inode to disk.
     130                 :            :  */
     131                 :         42 : int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
     132                 :            : {
     133                 :         42 :         int ret = 0, err;
     134                 :         42 :         bool needs_barrier = false;
     135                 :         42 :         struct inode *inode = file->f_mapping->host;
     136                 :         42 :         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     137                 :            : 
     138         [ +  - ]:         42 :         if (unlikely(ext4_forced_shutdown(sbi)))
     139                 :            :                 return -EIO;
     140                 :            : 
     141         [ -  + ]:         42 :         J_ASSERT(ext4_journal_current_handle() == NULL);
     142                 :            : 
     143                 :         42 :         trace_ext4_sync_file_enter(file, datasync);
     144                 :            : 
     145         [ -  + ]:         42 :         if (sb_rdonly(inode->i_sb)) {
     146                 :            :                 /* Make sure that we read updated s_mount_flags value */
     147                 :          0 :                 smp_rmb();
     148         [ #  # ]:          0 :                 if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
     149                 :          0 :                         ret = -EROFS;
     150                 :          0 :                 goto out;
     151                 :            :         }
     152                 :            : 
     153                 :         42 :         ret = file_write_and_wait_range(file, start, end);
     154         [ +  - ]:         42 :         if (ret)
     155                 :            :                 return ret;
     156                 :            : 
     157                 :            :         /*
     158                 :            :          * data=writeback,ordered:
     159                 :            :          *  The caller's filemap_fdatawrite()/wait will sync the data.
     160                 :            :          *  Metadata is in the journal, we wait for proper transaction to
     161                 :            :          *  commit here.
     162                 :            :          *
     163                 :            :          * data=journal:
     164                 :            :          *  filemap_fdatawrite won't do anything (the buffers are clean).
     165                 :            :          *  ext4_force_commit will write the file data into the journal and
     166                 :            :          *  will wait on that.
     167                 :            :          *  filemap_fdatawait() will encounter a ton of newly-dirtied pages
     168                 :            :          *  (they were dirtied by commit).  But that's OK - the blocks are
     169                 :            :          *  safe in-journal, which is all fsync() needs to ensure.
     170                 :            :          */
     171         [ -  + ]:         42 :         if (!sbi->s_journal)
     172                 :          0 :                 ret = ext4_fsync_nojournal(inode, datasync, &needs_barrier);
     173         [ +  + ]:         42 :         else if (ext4_should_journal_data(inode))
     174                 :         21 :                 ret = ext4_force_commit(inode->i_sb);
     175                 :            :         else
     176                 :         21 :                 ret = ext4_fsync_journal(inode, datasync, &needs_barrier);
     177                 :            : 
     178         [ +  - ]:         42 :         if (needs_barrier) {
     179                 :          0 :                 err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
     180         [ #  # ]:          0 :                 if (!ret)
     181                 :          0 :                         ret = err;
     182                 :            :         }
     183                 :         42 : out:
     184                 :         42 :         err = file_check_and_advance_wb_err(file);
     185         [ +  - ]:         42 :         if (ret == 0)
     186                 :         42 :                 ret = err;
     187                 :         42 :         trace_ext4_sync_file_exit(inode, ret);
     188                 :         42 :         return ret;
     189                 :            : }