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vfs: take f_lock on modifying f_mode after open time

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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>
This commit is contained in:
Wu Fengguang 2010-03-05 13:42:01 -08:00 • committed by Linus Torvalds
parent 85f1fb72fa
commit 42e4960868
2 changed files with 4 additions and 0 deletions
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2
fs/file_table.c
View file

@ -393,7 +393,9 @@ retry:
continue; continue;
if (!(f->f_mode & FMODE_WRITE)) if (!(f->f_mode & FMODE_WRITE))
continue; continue;
spin_lock(&f->f_lock);
f->f_mode &= ~FMODE_WRITE; f->f_mode &= ~FMODE_WRITE;
spin_unlock(&f->f_lock);
if (file_check_writeable(f) != 0) if (file_check_writeable(f) != 0)
continue; continue;
file_release_write(f); file_release_write(f);

2
fs/nfsd/nfs4state.c
View file

@ -1998,7 +1998,9 @@ nfs4_file_downgrade(struct file *filp, unsigned int share_access)
{ {
if (share_access & NFS4_SHARE_ACCESS_WRITE) { if (share_access & NFS4_SHARE_ACCESS_WRITE) {
drop_file_write_access(filp); drop_file_write_access(filp);
spin_lock(&filp->f_lock);
filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE; filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
spin_unlock(&filp->f_lock);
} }
} }