/** * nfs_sillyrename - Perform a silly-rename of a dentry * @dir: inode of directory that contains dentry * @dentry: dentry to be sillyrenamed * * NFSv2/3 is stateless and the server doesn't know when the client is * holding a file open. To prevent application problems when a file is * unlinked while it's still open, the client performs a "silly-rename". * That is, it renames the file to a hidden file in the same directory, * and only performs the unlink once the last reference to it is put. * * The final cleanup is done during dentry_iput. * * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server * could take responsibility for keeping open files referenced. The server * would also need to ensure that opened-but-deleted files were kept over * reboots. However, we may not assume a server does so. (RFC 5661 * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can * use to advertise that it does this; some day we may take advantage of * it.)) */ int nfs_sillyrename(struct inode *dir, struct dentry *dentry) { static unsigned int sillycounter; const int fileidsize = sizeof(NFS_FILEID(dentry->d_inode))*2; const int countersize = sizeof(sillycounter)*2; const int slen = sizeof(".nfs")+fileidsize+countersize-1; char silly[slen+1]; struct dentry *sdentry; struct rpc_task *task; int error = -EIO; dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n", dentry->d_parent->d_name.name, dentry->d_name.name, dentry->d_count); nfs_inc_stats(dir, NFSIOS_SILLYRENAME); /* * We don't allow a dentry to be silly-renamed twice. */ error = -EBUSY; if (dentry->d_flags & DCACHE_NFSFS_RENAMED) goto out; sprintf(silly, ".nfs%*.*Lx", fileidsize, fileidsize, (unsigned long long)NFS_FILEID(dentry->d_inode)); /* Return delegation in anticipation of the rename */ NFS_PROTO(dentry->d_inode)->return_delegation(dentry->d_inode); sdentry = NULL; do { char *suffix = silly + slen - countersize; dput(sdentry); sillycounter++; sprintf(suffix, "%*.*x", countersize, countersize, sillycounter); dfprintk(VFS, "NFS: trying to rename %s to %s\n", dentry->d_name.name, silly); sdentry = lookup_one_len(silly, dentry->d_parent, slen); /* * N.B. Better to return EBUSY here ... it could be * dangerous to delete the file while it's in use. */ if (IS_ERR(sdentry)) goto out; } while (sdentry->d_inode != NULL); /* need negative lookup */ /* queue unlink first. Can't do this from rpc_release as it * has to allocate memory */ error = nfs_async_unlink(dir, dentry); if (error) goto out_dput; /* populate unlinkdata with the right dname */ error = nfs_copy_dname(sdentry, (struct nfs_unlinkdata *)dentry->d_fsdata); if (error) { nfs_cancel_async_unlink(dentry); goto out_dput; } /* run the rename task, undo unlink if it fails */ task = nfs_async_rename(dir, dir, dentry, sdentry); if (IS_ERR(task)) { error = -EBUSY; nfs_cancel_async_unlink(dentry); goto out_dput; } /* wait for the RPC task to complete, unless a SIGKILL intervenes */ error = rpc_wait_for_completion_task(task); if (error == 0) error = task->tk_status; switch (error) { case 0: /* The rename succeeded */ nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); d_move(dentry, sdentry); break; case -ERESTARTSYS: /* The result of the rename is unknown. Play it safe by * forcing a new lookup */ d_drop(dentry); d_drop(sdentry); } rpc_put_task(task); out_dput: dput(sdentry); out: return error; }
int nfs_sillyrename(struct inode *dir, struct dentry *dentry) { static unsigned int sillycounter; const int fileidsize = sizeof(NFS_FILEID(dentry->d_inode))*2; const int countersize = sizeof(sillycounter)*2; const int slen = sizeof(".nfs")+fileidsize+countersize-1; char silly[slen+1]; struct dentry *sdentry; struct rpc_task *task; int error = -EIO; dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n", dentry->d_parent->d_name.name, dentry->d_name.name, dentry->d_count); nfs_inc_stats(dir, NFSIOS_SILLYRENAME); error = -EBUSY; if (dentry->d_flags & DCACHE_NFSFS_RENAMED) goto out; sprintf(silly, ".nfs%*.*Lx", fileidsize, fileidsize, (unsigned long long)NFS_FILEID(dentry->d_inode)); nfs_inode_return_delegation(dentry->d_inode); sdentry = NULL; do { char *suffix = silly + slen - countersize; dput(sdentry); sillycounter++; sprintf(suffix, "%*.*x", countersize, countersize, sillycounter); dfprintk(VFS, "NFS: trying to rename %s to %s\n", dentry->d_name.name, silly); sdentry = lookup_one_len(silly, dentry->d_parent, slen); if (IS_ERR(sdentry)) goto out; } while (sdentry->d_inode != NULL); error = nfs_async_unlink(dir, dentry); if (error) goto out_dput; error = nfs_copy_dname(sdentry, (struct nfs_unlinkdata *)dentry->d_fsdata); if (error) { nfs_cancel_async_unlink(dentry); goto out_dput; } task = nfs_async_rename(dir, dir, dentry, sdentry); if (IS_ERR(task)) { error = -EBUSY; nfs_cancel_async_unlink(dentry); goto out_dput; } error = rpc_wait_for_completion_task(task); if (error == 0) error = task->tk_status; switch (error) { case 0: /* The rename succeeded */ nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); d_move(dentry, sdentry); break; case -ERESTARTSYS: /* The result of the rename is unknown. Play it safe by * forcing a new lookup */ d_drop(dentry); d_drop(sdentry); } rpc_put_task(task); out_dput: dput(sdentry); out: return error; }