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ext2: Silence lockdep warning about reclaim under xattr_sem
Lockdep complains about a chain: sb_internal#2 --> &ei->xattr_sem#2 --> fs_reclaim and shrink_dentry_list -> ext2_evict_inode -> ext2_xattr_delete_inode -> down_write(ei->xattr_sem) creating a locking cycle in the reclaim path. This is however a false positive because when we are in ext2_evict_inode() we are the only holder of the inode reference and nobody else should touch xattr_sem of that inode. So we cannot ever block on acquiring the xattr_sem in the reclaim path. Silence the lockdep warning by using down_write_trylock() in ext2_xattr_delete_inode() to not create false locking dependency. Reported-by: "J. R. Okajima" <hooanon05g@gmail.com> Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com> Signed-off-by: Jan Kara <jack@suse.cz>
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@ -790,7 +790,15 @@ ext2_xattr_delete_inode(struct inode *inode)
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struct buffer_head *bh = NULL;
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struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
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down_write(&EXT2_I(inode)->xattr_sem);
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/*
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* We are the only ones holding inode reference. The xattr_sem should
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* better be unlocked! We could as well just not acquire xattr_sem at
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* all but this makes the code more futureproof. OTOH we need trylock
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* here to avoid false-positive warning from lockdep about reclaim
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* circular dependency.
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*/
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if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem)))
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return;
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if (!EXT2_I(inode)->i_file_acl)
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goto cleanup;
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