From d192a8e5c6fec4fe8cdafebccc415db4074dee88 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Thu, 5 May 2011 12:35:40 +0100 Subject: GFS2: Double check link count under glock To avoid any possible races relating to the link count, we need to recheck it under the inode's glock in all cases where it matters. Also to ensure we never get any nasty surprises, this patch also ensures that once the link count has hit zero it can never be elevated by rereading in data from disk. The only place we cannot provide a proper solution is in rename in the case where we are removing a target inode and we discover that the target inode has been already unlinked on another node. The race window is very small, and we return EAGAIN in this case to indicate what has happened. The proper solution would be to move the lookup parts of rename from the vfs into library calls which the fs could call directly, but that is potentially a very big job and this fix should cover most cases for now. Signed-off-by: Steven Whitehouse --- fs/gfs2/ops_inode.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) (limited to 'fs/gfs2/ops_inode.c') diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c index 09e436a5072..1005f9eb456 100644 --- a/fs/gfs2/ops_inode.c +++ b/fs/gfs2/ops_inode.c @@ -162,6 +162,10 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir, if (error) goto out_child; + error = -ENOENT; + if (inode->i_nlink == 0) + goto out_gunlock; + error = gfs2_permission(dir, MAY_WRITE | MAY_EXEC, 0); if (error) goto out_gunlock; @@ -335,6 +339,10 @@ static int gfs2_unlink(struct inode *dir, struct dentry *dentry) if (error) goto out_child; + error = -ENOENT; + if (ip->i_inode.i_nlink == 0) + goto out_rgrp; + error = gfs2_glock_nq(ghs + 2); /* rgrp */ if (error) goto out_rgrp; @@ -589,6 +597,10 @@ static int gfs2_rmdir(struct inode *dir, struct dentry *dentry) if (error) goto out_child; + error = -ENOENT; + if (ip->i_inode.i_nlink == 0) + goto out_rgrp; + error = gfs2_glock_nq(ghs + 2); /* rgrp */ if (error) goto out_rgrp; @@ -792,6 +804,10 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry, goto out_gunlock; } + error = -ENOENT; + if (ip->i_inode.i_nlink == 0) + goto out_gunlock; + /* Check out the old directory */ error = gfs2_unlink_ok(odip, &odentry->d_name, ip); @@ -805,6 +821,11 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry, if (error) goto out_gunlock; + if (nip->i_inode.i_nlink == 0) { + error = -EAGAIN; + goto out_gunlock; + } + if (S_ISDIR(nip->i_inode.i_mode)) { if (nip->i_entries < 2) { if (gfs2_consist_inode(nip)) @@ -835,7 +856,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry, if (odip != ndip) { if (!ndip->i_inode.i_nlink) { - error = -EINVAL; + error = -ENOENT; goto out_gunlock; } if (ndip->i_entries == (u32)-1) { -- cgit v1.2.3-70-g09d2