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author | Jan Kara <jack@suse.com> | 2015-12-07 14:34:49 -0500 |
---|---|---|
committer | Sasha Levin <sasha.levin@oracle.com> | 2016-03-23 10:20:24 -0400 |
commit | f2b132595b89d9236b386e1d6ed3fcf5e9edf4cb (patch) | |
tree | 38154cb60c0c2010f6113246b89764c4d5f5ecdc | |
parent | 181aaebde9360b8235df647ee36dafdc041d4964 (diff) | |
download | lwn-f2b132595b89d9236b386e1d6ed3fcf5e9edf4cb.tar.gz lwn-f2b132595b89d9236b386e1d6ed3fcf5e9edf4cb.zip |
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>
Reviewed-by: Mingming Cao <mingming.cao@oracle.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r-- | fs/ext4/ext4.h | 3 | ||||
-rw-r--r-- | fs/ext4/extents.c | 5 | ||||
-rw-r--r-- | fs/ext4/inode.c | 35 |
3 files changed, 42 insertions, 1 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 6b761efb4ec4..95dfff88de11 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2642,6 +2642,9 @@ static inline int ext4_update_inode_size(struct inode *inode, loff_t newsize) return changed; } +int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, + loff_t len); + struct ext4_group_info { unsigned long bb_state; struct rb_root bb_free_root; diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 8d16a01a0bf0..ea12f565be24 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4824,6 +4824,11 @@ static long ext4_zero_range(struct file *file, loff_t offset, * released from page cache. */ down_write(&EXT4_I(inode)->i_mmap_sem); + ret = ext4_update_disksize_before_punch(inode, offset, len); + if (ret) { + up_write(&EXT4_I(inode)->i_mmap_sem); + goto out_dio; + } /* Now release the pages and zero block aligned part of pages */ truncate_pagecache_range(inode, start, end - 1); inode->i_mtime = inode->i_ctime = ext4_current_time(inode); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d9236b84685d..3291e1af0e24 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3524,6 +3524,35 @@ 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 * @@ -3601,9 +3630,13 @@ 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); |