From: Eryu Guan Date: Thu, 22 Mar 2018 15:44:59 +0000 (-0400) Subject: ext4: update i_disksize if direct write past ondisk size X-Git-Tag: Ubuntu-5.2.0-15.16~4702^2~20 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=45d8ec4d9fd5468c08f2ef0b2b132bb62dc81a3d;p=mirror_ubuntu-eoan-kernel.git ext4: update i_disksize if direct write past ondisk size Currently in ext4 direct write path, we update i_disksize only when new eof is greater than i_size, and don't update it even when new eof is greater than i_disksize but less than i_size. This doesn't work well with delalloc buffer write, which updates i_size and i_disksize only when delalloc blocks are resolved (at writeback time), the i_disksize from direct write can be lost if a previous buffer write succeeded at write time but failed at writeback time, then results in corrupted ondisk inode size. Consider this case, first buffer write 4k data to a new file at offset 16k with delayed allocation, then direct write 4k data to the same file at offset 4k before delalloc blocks are resolved, which doesn't update i_disksize because it writes within i_size(20k), but the extent tree metadata has been committed in journal. Then writeback of the delalloc blocks fails (due to device error etc.), and i_size/i_disksize from buffer write can't be written to disk (still zero). A subsequent umount/mount cycle recovers journal and writes extent tree metadata from direct write to disk, but with i_disksize being zero. Fix it by updating i_disksize too in direct write path when new eof is greater than i_disksize but less than i_size, so i_disksize is always consistent with direct write. This fixes occasional i_size corruption in fstests generic/475. Signed-off-by: Eryu Guan Signed-off-by: Theodore Ts'o --- diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index bff44b4a0783..9acac476c15c 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3658,6 +3658,7 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter) { struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; + struct ext4_inode_info *ei = EXT4_I(inode); ssize_t ret; loff_t offset = iocb->ki_pos; size_t count = iov_iter_count(iter); @@ -3668,7 +3669,7 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter) int orphan = 0; handle_t *handle; - if (final_size > inode->i_size) { + if (final_size > inode->i_size || final_size > ei->i_disksize) { /* Credits for sb + inode write */ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2); if (IS_ERR(handle)) { @@ -3788,9 +3789,10 @@ static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter) ext4_orphan_del(handle, inode); if (ret > 0) { loff_t end = offset + ret; - if (end > inode->i_size) { + if (end > inode->i_size || end > ei->i_disksize) { ext4_update_i_disksize(inode, end); - i_size_write(inode, end); + if (end > inode->i_size) + i_size_write(inode, end); /* * We're going to return a positive `ret' * here due to non-zero-length I/O, so there's