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ext4: move inode extension/truncate code out from ->iomap_end() callback

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In preparation for implementing the iomap direct I/O modifications,
the inode extension/truncate code needs to be moved out from the
ext4_iomap_end() callback. For direct I/O, if the current code
remained, it would behave incorrrectly. Updating the inode size prior
to converting unwritten extents would potentially allow a racing
direct I/O read to find unwritten extents before being converted
correctly.

The inode extension/truncate code now resides within a new helper
ext4_handle_inode_extension(). This function has been designed so that
it can accommodate for both DAX and direct I/O extension/truncate
operations.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/d41ffa26e20b15b12895812c3cad7c91a6a59bc6.1572949325.git.mbobrowski@mbobrowski.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Matthew Bobrowski
2019-11-05 23:01:51 +11:00
committed by Theodore Ts'o
parent b1b4705d54
commit 569342dc24
2 changed files with 89 additions and 48 deletions
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48
fs/ext4/inode.c
View File

@@ -3583,53 +3583,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
ssize_t written, unsigned flags, struct iomap *iomap)
{
int ret = 0;
handle_t *handle;
int blkbits = inode->i_blkbits;
bool truncate = false;
if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
return 0;
handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto orphan_del;
}
if (ext4_update_inode_size(inode, offset + written))
ext4_mark_inode_dirty(handle, inode);
/*
* We may need to truncate allocated but not written blocks beyond EOF.
*/
if (iomap->offset + iomap->length >
ALIGN(inode->i_size, 1 << blkbits)) {
ext4_lblk_t written_blk, end_blk;
written_blk = (offset + written) >> blkbits;
end_blk = (offset + length) >> blkbits;
if (written_blk < end_blk && ext4_can_truncate(inode))
truncate = true;
}
/*
* Remove inode from orphan list if we were extending a inode and
* everything went fine.
*/
if (!truncate && inode->i_nlink &&
!list_empty(&EXT4_I(inode)->i_orphan))
ext4_orphan_del(handle, inode);
ext4_journal_stop(handle);
if (truncate) {
ext4_truncate_failed_write(inode);
orphan_del:
/*
* If truncate failed early the inode might still be on the
* orphan list; we need to make sure the inode is removed from
* the orphan list in that case.
*/
if (inode->i_nlink)
ext4_orphan_del(NULL, inode);
}
return ret;
return 0;
}
const struct iomap_ops ext4_iomap_ops = {