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author | Jan Kara <jack@suse.com> | 2015-12-07 14:34:49 -0500 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2015-12-07 14:34:49 -0500 |
commit | 011278485ecc3cd2a3954b5d4c73101d919bf1fa (patch) | |
tree | 740938e00aa0c972db386b5576656e646c02e36d /fs/ext4/inode.c | |
parent | 32ebffd3bbb4162da5ff88f9a35dd32d0a28ea70 (diff) | |
download | op-kernel-dev-011278485ecc3cd2a3954b5d4c73101d919bf1fa.zip op-kernel-dev-011278485ecc3cd2a3954b5d4c73101d919bf1fa.tar.gz |
ext4: fix races of writeback with punch hole and zero range
When doing delayed allocation, update of on-disk inode size is postponed
until IO submission time. However hole punch or zero range fallocate
calls can end up discarding the tail page cache page and thus on-disk
inode size would never be properly updated.
Make sure the on-disk inode size is updated before truncating page
cache.
Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/inode.c')
-rw-r--r-- | fs/ext4/inode.c | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d1207d0..472e608 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3559,6 +3559,35 @@ int ext4_can_truncate(struct inode *inode) } /* + * We have to make sure i_disksize gets properly updated before we truncate + * page cache due to hole punching or zero range. Otherwise i_disksize update + * can get lost as it may have been postponed to submission of writeback but + * that will never happen after we truncate page cache. + */ +int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, + loff_t len) +{ + handle_t *handle; + loff_t size = i_size_read(inode); + + WARN_ON(!mutex_is_locked(&inode->i_mutex)); + if (offset > size || offset + len < size) + return 0; + + if (EXT4_I(inode)->i_disksize >= size) + return 0; + + handle = ext4_journal_start(inode, EXT4_HT_MISC, 1); + if (IS_ERR(handle)) + return PTR_ERR(handle); + ext4_update_i_disksize(inode, size); + ext4_mark_inode_dirty(handle, inode); + ext4_journal_stop(handle); + + return 0; +} + +/* * ext4_punch_hole: punches a hole in a file by releaseing the blocks * associated with the given offset and length * @@ -3636,9 +3665,13 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) last_block_offset = round_down((offset + length), sb->s_blocksize) - 1; /* Now release the pages and zero block aligned part of pages*/ - if (last_block_offset > first_block_offset) + if (last_block_offset > first_block_offset) { + ret = ext4_update_disksize_before_punch(inode, offset, length); + if (ret) + goto out_dio; truncate_pagecache_range(inode, first_block_offset, last_block_offset); + } if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) credits = ext4_writepage_trans_blocks(inode); |