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Commit f7ab34ea authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext3: Add replace-on-truncate hueristics for data=writeback mode 



In data=writeback mode, start an asynchronous flush when closing a
file which had been previously truncated down to zero.  This lowers
the probability of data loss in the case of applications that attempt
to replace a file using truncate.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 512a0043

fs/ext3/file.c

+4 −0
Original line number Diff line number Diff line
@@ -33,6 +33,10 @@ 
 */

static int ext3_release_file (struct inode * inode, struct file * filp)

{

	if (EXT3_I(inode)->i_state & EXT3_STATE_FLUSH_ON_CLOSE) {

		filemap_flush(inode->i_mapping);

		EXT3_I(inode)->i_state &= ~EXT3_STATE_FLUSH_ON_CLOSE;

	}

	/* if we are the last writer on the inode, drop the block reservation */

	if ((filp->f_mode & FMODE_WRITE) &&

			(atomic_read(&inode->i_writecount) == 1))

fs/ext3/inode.c

+3 −0
Original line number Diff line number Diff line
@@ -2346,6 +2346,9 @@ void ext3_truncate(struct inode *inode) 
	if (!ext3_can_truncate(inode))

		return;



	if (inode->i_size == 0 && ext3_should_writeback_data(inode))

		ei->i_state |= EXT3_STATE_FLUSH_ON_CLOSE;



	/*

	 * We have to lock the EOF page here, because lock_page() nests

	 * outside journal_start().

include/linux/ext3_fs.h

+1 −0
Original line number Diff line number Diff line
@@ -208,6 +208,7 @@ static inline __u32 ext3_mask_flags(umode_t mode, __u32 flags) 
#define EXT3_STATE_JDATA		0x00000001 /* journaled data exists */

#define EXT3_STATE_NEW			0x00000002 /* inode is newly created */

#define EXT3_STATE_XATTR		0x00000004 /* has in-inode xattrs */

#define EXT3_STATE_FLUSH_ON_CLOSE	0x00000008



/* Used to pass group descriptor data when online resize is done */

struct ext3_new_group_input {