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NFS: Fix a potential race between umount and nfs_access_cache_shrinker()
Thanks to Yawei Niu for spotting the race. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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parent
e6f8107595
commit
6f23e3872c
11
fs/nfs/dir.c
11
fs/nfs/dir.c
@ -1694,13 +1694,19 @@ int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
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restart:
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spin_lock(&nfs_access_lru_lock);
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list_for_each_entry(nfsi, &nfs_access_lru_list, access_cache_inode_lru) {
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struct rw_semaphore *s_umount;
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struct inode *inode;
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if (nr_to_scan-- == 0)
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break;
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inode = igrab(&nfsi->vfs_inode);
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if (inode == NULL)
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s_umount = &nfsi->vfs_inode.i_sb->s_umount;
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if (!down_read_trylock(s_umount))
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continue;
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inode = igrab(&nfsi->vfs_inode);
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if (inode == NULL) {
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up_read(s_umount);
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continue;
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}
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spin_lock(&inode->i_lock);
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if (list_empty(&nfsi->access_cache_entry_lru))
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goto remove_lru_entry;
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@ -1719,6 +1725,7 @@ remove_lru_entry:
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spin_unlock(&inode->i_lock);
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spin_unlock(&nfs_access_lru_lock);
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iput(inode);
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up_read(s_umount);
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goto restart;
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}
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spin_unlock(&nfs_access_lru_lock);
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