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btrfs: disable defrag on pre-content watched files

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We queue up inodes to be defrag'ed asynchronously, which means we do not
have their original file for readahead.  This means that the code to
skip readahead on pre-content watched files will not run, and we could
potentially read in empty pages.

Handle this corner case by disabling defrag on files that are currently
being watched for pre-content events.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/4cc5bcea13db7904174353d08e85157356282a59.1731684329.git.josef@toxicpanda.com
This commit is contained in:
Josef Bacik
2024-11-15 10:30:31 -05:00
committed by Jan Kara
parent 7f4796a465
commit b722e40be2
1 changed files with 9 additions and 0 deletions
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9
fs/btrfs/ioctl.c
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@@ -2635,6 +2635,15 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
goto out;
}
/*
* Don't allow defrag on pre-content watched files, as it could
* populate the page cache with 0's via readahead.
*/
if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) {
ret = -EINVAL;
goto out;
}
if (argp) {
if (copy_from_user(&range, argp, sizeof(range))) {
ret = -EFAULT;