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ext4: check and update i_disksize properly

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After commit 3da40c7b0898 ("ext4: only call ext4_truncate when size <=
isize"), i_disksize could always be updated to i_size in ext4_setattr(),
and we could sure that i_disksize <= i_size since holding inode lock and
if i_disksize < i_size there are delalloc writes pending in the range
upto i_size. If the end of the current write is <= i_size, there's no
need to touch i_disksize since writeback will push i_disksize upto
i_size eventually. So we can switch to check i_size instead of
i_disksize in ext4_da_write_end() when write to the end of the file.
we also could remove ext4_mark_inode_dirty() together because we defer
inode dirtying to generic_write_end() or ext4_da_write_inline_data_end().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210716122024.1105856-2-yi.zhang@huawei.com
This commit is contained in:
Zhang Yi 2021-07-16 20:20:21 +08:00 committed by Theodore Ts'o
parent b33d9f5909
commit 4df031ff58
1 changed files with 18 additions and 16 deletions
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34
fs/ext4/inode.c
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@ -3084,35 +3084,37 @@ static int ext4_da_write_end(struct file *file,
end = start + copied - 1;
/*
* generic_write_end() will run mark_inode_dirty() if i_size
* changes. So let's piggyback the i_disksize mark_inode_dirty
* into that.
* Since we are holding inode lock, we are sure i_disksize <=
* i_size. We also know that if i_disksize < i_size, there are
* delalloc writes pending in the range upto i_size. If the end of
* the current write is <= i_size, there's no need to touch
* i_disksize since writeback will push i_disksize upto i_size
* eventually. If the end of the current write is > i_size and
* inside an allocated block (ext4_da_should_update_i_disksize()
* check), we need to update i_disksize here as neither
* ext4_writepage() nor certain ext4_writepages() paths not
* allocating blocks update i_disksize.
*
* Note that we defer inode dirtying to generic_write_end() /
* ext4_da_write_inline_data_end().
*/
new_i_size = pos + copied;
if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
if (copied && new_i_size > inode->i_size) {
if (ext4_has_inline_data(inode) ||
ext4_da_should_update_i_disksize(page, end)) {
ext4_da_should_update_i_disksize(page, end))
ext4_update_i_disksize(inode, new_i_size);
/* We need to mark inode dirty even if
* new_i_size is less that inode->i_size
* bu greater than i_disksize.(hint delalloc)
*/
ret = ext4_mark_inode_dirty(handle, inode);
}
}
if (write_mode != CONVERT_INLINE_DATA &&
ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
ext4_has_inline_data(inode))
ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
ret = ext4_da_write_inline_data_end(inode, pos, len, copied,
page);
else
ret2 = generic_write_end(file, mapping, pos, len, copied,
ret = generic_write_end(file, mapping, pos, len, copied,
page, fsdata);
copied = ret2;
if (ret2 < 0)
ret = ret2;
copied = ret;
ret2 = ext4_journal_stop(handle);
if (unlikely(ret2 && !ret))
ret = ret2;