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NFS: Avoid changing nlink when file removes and attribute updates race

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If a file removal races with another operation that updates its
attributes, then skip the change to nlink, and just mark the attributes
as being stale.

Reported-by: Aiden Lambert <alambert48@gatech.edu>
Fixes: 59a707b0d4 ("NFS: Ensure we revalidate the inode correctly after remove or rename")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2025-11-17 15:28:17 -05:00
parent 6a23ae0a96
commit bd4928ec79
1 changed files with 13 additions and 6 deletions
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19
fs/nfs/dir.c
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@ -1894,13 +1894,15 @@ static int nfs_dentry_delete(const struct dentry *dentry)
}
/* Ensure that we revalidate inode->i_nlink */
static void nfs_drop_nlink(struct inode *inode)
static void nfs_drop_nlink(struct inode *inode, unsigned long gencount)
{
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&inode->i_lock);
/* drop the inode if we're reasonably sure this is the last link */
if (inode->i_nlink > 0)
if (inode->i_nlink > 0 && gencount == nfsi->attr_gencount)
drop_nlink(inode);
NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
nfsi->attr_gencount = nfs_inc_attr_generation_counter();
nfs_set_cache_invalid(
inode, NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_CTIME |
NFS_INO_INVALID_NLINK);
@ -1914,8 +1916,9 @@ static void nfs_drop_nlink(struct inode *inode)
static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
{
if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
unsigned long gencount = READ_ONCE(NFS_I(inode)->attr_gencount);
nfs_complete_unlink(dentry, inode);
nfs_drop_nlink(inode);
nfs_drop_nlink(inode, gencount);
}
iput(inode);
}
@ -2507,9 +2510,11 @@ static int nfs_safe_remove(struct dentry *dentry)
trace_nfs_remove_enter(dir, dentry);
if (inode != NULL) {
unsigned long gencount = READ_ONCE(NFS_I(inode)->attr_gencount);
error = NFS_PROTO(dir)->remove(dir, dentry);
if (error == 0)
nfs_drop_nlink(inode);
nfs_drop_nlink(inode, gencount);
} else
error = NFS_PROTO(dir)->remove(dir, dentry);
if (error == -ENOENT)
@ -2709,6 +2714,7 @@ int nfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
{
struct inode *old_inode = d_inode(old_dentry);
struct inode *new_inode = d_inode(new_dentry);
unsigned long new_gencount = 0;
struct dentry *dentry = NULL;
struct rpc_task *task;
bool must_unblock = false;
@ -2761,6 +2767,7 @@ int nfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
} else {
block_revalidate(new_dentry);
must_unblock = true;
new_gencount = NFS_I(new_inode)->attr_gencount;
spin_unlock(&new_dentry->d_lock);
}
@ -2800,7 +2807,7 @@ int nfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
new_dir, new_dentry, error);
if (!error) {
if (new_inode != NULL)
nfs_drop_nlink(new_inode);
nfs_drop_nlink(new_inode, new_gencount);
/*
* The d_move() should be here instead of in an async RPC completion
* handler because we need the proper locks to move the dentry. If