diff options
Diffstat (limited to 'fs/nfs/unlink.c')
| -rw-r--r-- | fs/nfs/unlink.c | 521 |
1 files changed, 521 insertions, 0 deletions
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c new file mode 100644 index 000000000..b27ebdcce --- /dev/null +++ b/fs/nfs/unlink.c @@ -0,0 +1,521 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/nfs/unlink.c + * + * nfs sillydelete handling + * + */ + +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/dcache.h> +#include <linux/sunrpc/sched.h> +#include <linux/sunrpc/clnt.h> +#include <linux/nfs_fs.h> +#include <linux/sched.h> +#include <linux/wait.h> +#include <linux/namei.h> +#include <linux/fsnotify.h> + +#include "internal.h" +#include "nfs4_fs.h" +#include "iostat.h" +#include "delegation.h" + +#include "nfstrace.h" + +/** + * nfs_free_unlinkdata - release data from a sillydelete operation. + * @data: pointer to unlink structure. + */ +static void +nfs_free_unlinkdata(struct nfs_unlinkdata *data) +{ + put_cred(data->cred); + kfree(data->args.name.name); + kfree(data); +} + +/** + * nfs_async_unlink_done - Sillydelete post-processing + * @task: rpc_task of the sillydelete + * @calldata: pointer to nfs_unlinkdata + * + * Do the directory attribute update. + */ +static void nfs_async_unlink_done(struct rpc_task *task, void *calldata) +{ + struct nfs_unlinkdata *data = calldata; + struct inode *dir = d_inode(data->dentry->d_parent); + + trace_nfs_sillyrename_unlink(data, task->tk_status); + if (!NFS_PROTO(dir)->unlink_done(task, dir)) + rpc_restart_call_prepare(task); +} + +/** + * nfs_async_unlink_release - Release the sillydelete data. + * @calldata: struct nfs_unlinkdata to release + * + * We need to call nfs_put_unlinkdata as a 'tk_release' task since the + * rpc_task would be freed too. + */ +static void nfs_async_unlink_release(void *calldata) +{ + struct nfs_unlinkdata *data = calldata; + struct dentry *dentry = data->dentry; + struct super_block *sb = dentry->d_sb; + + up_read_non_owner(&NFS_I(d_inode(dentry->d_parent))->rmdir_sem); + d_lookup_done(dentry); + nfs_free_unlinkdata(data); + dput(dentry); + nfs_sb_deactive(sb); +} + +static void nfs_unlink_prepare(struct rpc_task *task, void *calldata) +{ + struct nfs_unlinkdata *data = calldata; + struct inode *dir = d_inode(data->dentry->d_parent); + NFS_PROTO(dir)->unlink_rpc_prepare(task, data); +} + +static const struct rpc_call_ops nfs_unlink_ops = { + .rpc_call_done = nfs_async_unlink_done, + .rpc_release = nfs_async_unlink_release, + .rpc_call_prepare = nfs_unlink_prepare, +}; + +static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data) +{ + struct rpc_message msg = { + .rpc_argp = &data->args, + .rpc_resp = &data->res, + .rpc_cred = data->cred, + }; + struct rpc_task_setup task_setup_data = { + .rpc_message = &msg, + .callback_ops = &nfs_unlink_ops, + .callback_data = data, + .workqueue = nfsiod_workqueue, + .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF, + }; + struct rpc_task *task; + struct inode *dir = d_inode(data->dentry->d_parent); + nfs_sb_active(dir->i_sb); + data->args.fh = NFS_FH(dir); + nfs_fattr_init(data->res.dir_attr); + + NFS_PROTO(dir)->unlink_setup(&msg, data->dentry, inode); + + task_setup_data.rpc_client = NFS_CLIENT(dir); + task = rpc_run_task(&task_setup_data); + if (!IS_ERR(task)) + rpc_put_task_async(task); +} + +static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data) +{ + struct inode *dir = d_inode(dentry->d_parent); + struct dentry *alias; + + down_read_non_owner(&NFS_I(dir)->rmdir_sem); + alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq); + if (IS_ERR(alias)) { + up_read_non_owner(&NFS_I(dir)->rmdir_sem); + return 0; + } + if (!d_in_lookup(alias)) { + int ret; + void *devname_garbage = NULL; + + /* + * Hey, we raced with lookup... See if we need to transfer + * the sillyrename information to the aliased dentry. + */ + spin_lock(&alias->d_lock); + if (d_really_is_positive(alias) && + !(alias->d_flags & DCACHE_NFSFS_RENAMED)) { + devname_garbage = alias->d_fsdata; + alias->d_fsdata = data; + alias->d_flags |= DCACHE_NFSFS_RENAMED; + ret = 1; + } else + ret = 0; + spin_unlock(&alias->d_lock); + dput(alias); + up_read_non_owner(&NFS_I(dir)->rmdir_sem); + /* + * If we'd displaced old cached devname, free it. At that + * point dentry is definitely not a root, so we won't need + * that anymore. + */ + kfree(devname_garbage); + return ret; + } + data->dentry = alias; + nfs_do_call_unlink(inode, data); + return 1; +} + +/** + * nfs_async_unlink - asynchronous unlinking of a file + * @dentry: parent directory of dentry + * @name: name of dentry to unlink + */ +static int +nfs_async_unlink(struct dentry *dentry, const struct qstr *name) +{ + struct nfs_unlinkdata *data; + int status = -ENOMEM; + void *devname_garbage = NULL; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + if (data == NULL) + goto out; + data->args.name.name = kstrdup(name->name, GFP_KERNEL); + if (!data->args.name.name) + goto out_free; + data->args.name.len = name->len; + + data->cred = get_current_cred(); + data->res.dir_attr = &data->dir_attr; + init_waitqueue_head(&data->wq); + + status = -EBUSY; + spin_lock(&dentry->d_lock); + if (dentry->d_flags & DCACHE_NFSFS_RENAMED) + goto out_unlock; + dentry->d_flags |= DCACHE_NFSFS_RENAMED; + devname_garbage = dentry->d_fsdata; + dentry->d_fsdata = data; + spin_unlock(&dentry->d_lock); + /* + * If we'd displaced old cached devname, free it. At that + * point dentry is definitely not a root, so we won't need + * that anymore. + */ + kfree(devname_garbage); + return 0; +out_unlock: + spin_unlock(&dentry->d_lock); + put_cred(data->cred); + kfree(data->args.name.name); +out_free: + kfree(data); +out: + return status; +} + +/** + * nfs_complete_unlink - Initialize completion of the sillydelete + * @dentry: dentry to delete + * @inode: inode + * + * Since we're most likely to be called by dentry_iput(), we + * only use the dentry to find the sillydelete. We then copy the name + * into the qstr. + */ +void +nfs_complete_unlink(struct dentry *dentry, struct inode *inode) +{ + struct nfs_unlinkdata *data; + + spin_lock(&dentry->d_lock); + dentry->d_flags &= ~DCACHE_NFSFS_RENAMED; + data = dentry->d_fsdata; + dentry->d_fsdata = NULL; + spin_unlock(&dentry->d_lock); + + if (NFS_STALE(inode) || !nfs_call_unlink(dentry, inode, data)) + nfs_free_unlinkdata(data); +} + +/* Cancel a queued async unlink. Called when a sillyrename run fails. */ +static void +nfs_cancel_async_unlink(struct dentry *dentry) +{ + spin_lock(&dentry->d_lock); + if (dentry->d_flags & DCACHE_NFSFS_RENAMED) { + struct nfs_unlinkdata *data = dentry->d_fsdata; + + dentry->d_flags &= ~DCACHE_NFSFS_RENAMED; + dentry->d_fsdata = NULL; + spin_unlock(&dentry->d_lock); + nfs_free_unlinkdata(data); + return; + } + spin_unlock(&dentry->d_lock); +} + +/** + * nfs_async_rename_done - Sillyrename post-processing + * @task: rpc_task of the sillyrename + * @calldata: nfs_renamedata for the sillyrename + * + * Do the directory attribute updates and the d_move + */ +static void nfs_async_rename_done(struct rpc_task *task, void *calldata) +{ + struct nfs_renamedata *data = calldata; + struct inode *old_dir = data->old_dir; + struct inode *new_dir = data->new_dir; + struct dentry *old_dentry = data->old_dentry; + + trace_nfs_sillyrename_rename(old_dir, old_dentry, + new_dir, data->new_dentry, task->tk_status); + if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) { + rpc_restart_call_prepare(task); + return; + } + + if (data->complete) + data->complete(task, data); +} + +/** + * nfs_async_rename_release - Release the sillyrename data. + * @calldata: the struct nfs_renamedata to be released + */ +static void nfs_async_rename_release(void *calldata) +{ + struct nfs_renamedata *data = calldata; + struct super_block *sb = data->old_dir->i_sb; + + if (d_really_is_positive(data->old_dentry)) + nfs_mark_for_revalidate(d_inode(data->old_dentry)); + + /* The result of the rename is unknown. Play it safe by + * forcing a new lookup */ + if (data->cancelled) { + spin_lock(&data->old_dir->i_lock); + nfs_force_lookup_revalidate(data->old_dir); + spin_unlock(&data->old_dir->i_lock); + if (data->new_dir != data->old_dir) { + spin_lock(&data->new_dir->i_lock); + nfs_force_lookup_revalidate(data->new_dir); + spin_unlock(&data->new_dir->i_lock); + } + } + + dput(data->old_dentry); + dput(data->new_dentry); + iput(data->old_dir); + iput(data->new_dir); + nfs_sb_deactive(sb); + put_cred(data->cred); + kfree(data); +} + +static void nfs_rename_prepare(struct rpc_task *task, void *calldata) +{ + struct nfs_renamedata *data = calldata; + NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data); +} + +static const struct rpc_call_ops nfs_rename_ops = { + .rpc_call_done = nfs_async_rename_done, + .rpc_release = nfs_async_rename_release, + .rpc_call_prepare = nfs_rename_prepare, +}; + +/** + * nfs_async_rename - perform an asynchronous rename operation + * @old_dir: directory that currently holds the dentry to be renamed + * @new_dir: target directory for the rename + * @old_dentry: original dentry to be renamed + * @new_dentry: dentry to which the old_dentry should be renamed + * @complete: Function to run on successful completion + * + * It's expected that valid references to the dentries and inodes are held + */ +struct rpc_task * +nfs_async_rename(struct inode *old_dir, struct inode *new_dir, + struct dentry *old_dentry, struct dentry *new_dentry, + void (*complete)(struct rpc_task *, struct nfs_renamedata *)) +{ + struct nfs_renamedata *data; + struct rpc_message msg = { }; + struct rpc_task_setup task_setup_data = { + .rpc_message = &msg, + .callback_ops = &nfs_rename_ops, + .workqueue = nfsiod_workqueue, + .rpc_client = NFS_CLIENT(old_dir), + .flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF, + }; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + if (data == NULL) + return ERR_PTR(-ENOMEM); + task_setup_data.callback_data = data; + + data->cred = get_current_cred(); + + msg.rpc_argp = &data->args; + msg.rpc_resp = &data->res; + msg.rpc_cred = data->cred; + + /* set up nfs_renamedata */ + data->old_dir = old_dir; + ihold(old_dir); + data->new_dir = new_dir; + ihold(new_dir); + data->old_dentry = dget(old_dentry); + data->new_dentry = dget(new_dentry); + nfs_fattr_init(&data->old_fattr); + nfs_fattr_init(&data->new_fattr); + data->complete = complete; + + /* set up nfs_renameargs */ + data->args.old_dir = NFS_FH(old_dir); + data->args.old_name = &old_dentry->d_name; + data->args.new_dir = NFS_FH(new_dir); + data->args.new_name = &new_dentry->d_name; + + /* set up nfs_renameres */ + data->res.old_fattr = &data->old_fattr; + data->res.new_fattr = &data->new_fattr; + + nfs_sb_active(old_dir->i_sb); + + NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dentry, new_dentry); + + return rpc_run_task(&task_setup_data); +} + +/* + * Perform tasks needed when a sillyrename is done such as cancelling the + * queued async unlink if it failed. + */ +static void +nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data) +{ + struct dentry *dentry = data->old_dentry; + + if (task->tk_status != 0) { + nfs_cancel_async_unlink(dentry); + return; + } +} + +#define SILLYNAME_PREFIX ".nfs" +#define SILLYNAME_PREFIX_LEN ((unsigned)sizeof(SILLYNAME_PREFIX) - 1) +#define SILLYNAME_FILEID_LEN ((unsigned)sizeof(u64) << 1) +#define SILLYNAME_COUNTER_LEN ((unsigned)sizeof(unsigned int) << 1) +#define SILLYNAME_LEN (SILLYNAME_PREFIX_LEN + \ + SILLYNAME_FILEID_LEN + \ + SILLYNAME_COUNTER_LEN) + +/** + * 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; + unsigned char silly[SILLYNAME_LEN + 1]; + unsigned long long fileid; + struct dentry *sdentry; + struct inode *inode = d_inode(dentry); + struct rpc_task *task; + int error = -EBUSY; + + dfprintk(VFS, "NFS: silly-rename(%pd2, ct=%d)\n", + dentry, d_count(dentry)); + nfs_inc_stats(dir, NFSIOS_SILLYRENAME); + + /* + * We don't allow a dentry to be silly-renamed twice. + */ + if (dentry->d_flags & DCACHE_NFSFS_RENAMED) + goto out; + + fileid = NFS_FILEID(d_inode(dentry)); + + sdentry = NULL; + do { + int slen; + dput(sdentry); + sillycounter++; + slen = scnprintf(silly, sizeof(silly), + SILLYNAME_PREFIX "%0*llx%0*x", + SILLYNAME_FILEID_LEN, fileid, + SILLYNAME_COUNTER_LEN, sillycounter); + + dfprintk(VFS, "NFS: trying to rename %pd to %s\n", + dentry, 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 (d_inode(sdentry) != NULL); /* need negative lookup */ + + ihold(inode); + + /* queue unlink first. Can't do this from rpc_release as it + * has to allocate memory + */ + error = nfs_async_unlink(dentry, &sdentry->d_name); + if (error) + goto out_dput; + + /* run the rename task, undo unlink if it fails */ + task = nfs_async_rename(dir, dir, dentry, sdentry, + nfs_complete_sillyrename); + 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)); + spin_lock(&inode->i_lock); + NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter(); + NFS_I(inode)->cache_validity |= NFS_INO_INVALID_CHANGE + | NFS_INO_INVALID_CTIME + | NFS_INO_REVAL_FORCED; + spin_unlock(&inode->i_lock); + 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: + iput(inode); + dput(sdentry); +out: + return error; +} |