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Subjectquery re unlink() ... inotify ... open() race
Hi,

We're noticing a rare race here with open() in tail(1), where this happens:

tail --follow=name "file"
/* "file" is unlinked() by another process */
read(IN_ATTRIB from inotify); /* for st_nlink-- */
open("file") /* Done to check if deleted, but this succeeds! */

The open() succeeding is surprising. Is that allowed?
The summary of the sequence in the kernel is:

vfs_unlink() {
mutex_lock(&(dentry->d_inode->i_mutex));
security_inode_unlink(dir, dentry);
try_break_deleg(target, delegated_inode);
dir->i_op->unlink(dir, dentry);
dont_mount(dentry);
detach_mounts(dentry);
mutex_unlock(&(dentry->d_inode->i_mutex));

fsnotify_link_count(target)
d_delete(dentry);
}

thanks,
Pádraig.


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