Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 14:11:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

Btrfs: make sure not to defrag extents past i_size

Browse Source 
The btrfs file defrag code will loop through the extents and
force COW on them.  But there is a concurrent truncate in the middle of
the defrag, it might end up defragging the same range over and over
again.

The problem is that writepage won't go through and do anything on pages
past i_size, so the cow won't happen, so the file will appear to still
be fragmented.  defrag will end up hitting the same extents again and
again.

In the worst case, the truncate can actually live lock with the defrag
because the defrag keeps creating new ordered extents which the truncate
code keeps waiting on.

The fix here is to make defrag check for i_size inside the main loop,
instead of just once before the looping starts.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2011-10-11 11:41:40 -04:00
parent 2a0f7f5769
commit f7f43cc841
1 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/btrfs/ioctl.c
View File

@ -1062,7 +1062,9 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
if (i < inode->i_mapping->writeback_index)
inode->i_mapping->writeback_index = i;
while (i <= last_index && defrag_count < max_to_defrag) {
while (i <= last_index && defrag_count < max_to_defrag &&
(i < (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT)) {
/*
* make sure we stop running if someone unmounts
* the FS