[PATCH 1/6] sysfs: Serialize updates to the vfs inode
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From: Eric W. Biederman on 12 Feb 2010 22:30 From: Eric W. Biederman <ebiederm(a)aristanetworks.com> The vfs depends upon filesystem methods to update the vfs inode. Sysfs adds to the normal number of places where the vfs inode is updated by also updatng the vfs inode in sysfs_refresh_inode. Typically the inode mutex is used to serialize updates to the vfs inode, but grabbing the inode mutex in sysfs_permission and sysfs_getattr causes deadlocks, because sometimes the vfs calls those operations with the inode mutex held. Therefore sysfs can not use the inode mutex to serial updates to the vfs inode. The sysfs_mutex is acquired in all of the routines where sysfs updates the vfs inode, and with a small change we can consistently protext sysfs vfs inode updates with the sysfs_mutex. To protect the sysfs vfs inode updates with the sysfs_mutex simply requires extending the scope of sysfs_mutex in sysfs_setattr over inode_setattr, and over inode_change_ok (so we have an unchanging inode when we perform the check). Acked-by: Serge Hallyn <serue(a)us.ibm.com> Signed-off-by: Eric W. Biederman <ebiederm(a)aristanetworks.com> --- fs/sysfs/inode.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 6a06a1d..0d09f6c 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -111,20 +111,20 @@ int sysfs_setattr(struct dentry *dentry, struct iattr *iattr) if (!sd) return -EINVAL; + mutex_lock(&sysfs_mutex); error = inode_change_ok(inode, iattr); if (error) - return error; + goto out; iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ error = inode_setattr(inode, iattr); if (error) - return error; + goto out; - mutex_lock(&sysfs_mutex); error = sysfs_sd_setattr(sd, iattr); +out: mutex_unlock(&sysfs_mutex); - return error; } -- 1.6.5.2.143.g8cc62 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |