vfs: take f_lock on modifying f_mode after open time
We'll introduce FMODE_RANDOM which will be runtime modified. So protect all runtime modification to f_mode with f_lock to avoid races. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: <stable@kernel.org> [2.6.33.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -393,7 +393,9 @@ retry:
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continue;
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if (!(f->f_mode & FMODE_WRITE))
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continue;
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spin_lock(&f->f_lock);
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f->f_mode &= ~FMODE_WRITE;
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spin_unlock(&f->f_lock);
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if (file_check_writeable(f) != 0)
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continue;
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file_release_write(f);
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@ -1998,7 +1998,9 @@ nfs4_file_downgrade(struct file *filp, unsigned int share_access)
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{
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if (share_access & NFS4_SHARE_ACCESS_WRITE) {
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drop_file_write_access(filp);
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spin_lock(&filp->f_lock);
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filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
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spin_unlock(&filp->f_lock);
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}
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}
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