Shulou(Shulou.com)06/02 Report--

This article is to share with you about how to call the sync source code in the linux system, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Int sys_sync (void)

{

Int i

Struct buffer_head * bh

/ / write all inode to buffer and wait for write back, as shown in the following code

Sync_inodes (); / * write out inodes into buffers * /

Bh = start_buffer

For (iTun0; ib_dirt)

/ / request the underlying layer to write to the hard disk, waiting for the underlying driver to write back to the hard disk, not necessarily immediately

Ll_rw_block (WRITE,bh)

}

Return 0

}

Let's take a look at sync_inode. This function writes the inode node in inode table, that is, the file opened by the process, to buffer.

/ / iterate through all the inode, read the data blocks including the inode from the hard disk, and then use the inode of memory to overwrite the data read in the hard disk, store it in buffer, and wait for write back.

Void sync_inodes (void)

{

Int i

Struct m_inode * inode

Inode = 0+inode_table

For (iTun0; ii_dirt & &! inode- > i_pipe)

Write_inode (inode)

}

}

/ / first read the inode from the hard disk, then overwrite it, and wait for write back

Static void write_inode (struct m_inode * inode)

{

Struct super_block * sb

Struct buffer_head * bh

Int block

Lock_inode (inode)

If (! inode- > i_dirt | |! inode- > i_dev) {

Unlock_inode (inode)

Return

}

If (! (sb=get_super (inode- > i_dev)

Panic ("trying to write inode without device")

/ / calculate the block number of inode, the relative offset of 2 + inode bitmap blocks + block bitmap blocks + inode

Block = 2 + sb- > s_imap_blocks + sb- > s_zmap_blocks +

(inode- > i_num-1) / INODES_PER_BLOCK

/ / read the entire data block containing the inode

If (! (bh=bread (inode- > iDeign block)

Panic ("unable to read i-node block")

/ / find the location of the inode in the data block, write to the cache and wait for writing back to the hard disk

((struct d_inode *) bh- > b_data)

[(inode- > i_num-1)% INODES_PER_BLOCK] =

* (struct d_inode *) inode

Bh- > b_dirt=1

Inode- > i_dirt=0

Brelse (bh)

Unlock_inode (inode)

}

The above is how to call the sync source code in the linux system. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.