diff options
Diffstat (limited to 'fs/cachefiles/namei.c')
| -rw-r--r-- | fs/cachefiles/namei.c | 824 |
1 files changed, 824 insertions, 0 deletions
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c new file mode 100644 index 000000000..88955249a --- /dev/null +++ b/fs/cachefiles/namei.c @@ -0,0 +1,824 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles path walking and related routines + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/fs.h> +#include <linux/namei.h> +#include "internal.h" + +/* + * Mark the backing file as being a cache file if it's not already in use. The + * mark tells the culling request command that it's not allowed to cull the + * file or directory. The caller must hold the inode lock. + */ +static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object, + struct inode *inode) +{ + bool can_use = false; + + if (!(inode->i_flags & S_KERNEL_FILE)) { + inode->i_flags |= S_KERNEL_FILE; + trace_cachefiles_mark_active(object, inode); + can_use = true; + } else { + trace_cachefiles_mark_failed(object, inode); + } + + return can_use; +} + +static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object, + struct inode *inode) +{ + bool can_use; + + inode_lock(inode); + can_use = __cachefiles_mark_inode_in_use(object, inode); + inode_unlock(inode); + return can_use; +} + +/* + * Unmark a backing inode. The caller must hold the inode lock. + */ +static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object, + struct inode *inode) +{ + inode->i_flags &= ~S_KERNEL_FILE; + trace_cachefiles_mark_inactive(object, inode); +} + +static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object, + struct inode *inode) +{ + inode_lock(inode); + __cachefiles_unmark_inode_in_use(object, inode); + inode_unlock(inode); +} + +/* + * Unmark a backing inode and tell cachefilesd that there's something that can + * be culled. + */ +void cachefiles_unmark_inode_in_use(struct cachefiles_object *object, + struct file *file) +{ + struct cachefiles_cache *cache = object->volume->cache; + struct inode *inode = file_inode(file); + + cachefiles_do_unmark_inode_in_use(object, inode); + + if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { + atomic_long_add(inode->i_blocks, &cache->b_released); + if (atomic_inc_return(&cache->f_released)) + cachefiles_state_changed(cache); + } +} + +/* + * get a subdirectory + */ +struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, + struct dentry *dir, + const char *dirname, + bool *_is_new) +{ + struct dentry *subdir; + struct path path; + int ret; + + _enter(",,%s", dirname); + + /* search the current directory for the element name */ + +retry: + ret = cachefiles_inject_read_error(); + if (ret == 0) + subdir = start_creating(&nop_mnt_idmap, dir, &QSTR(dirname)); + else + subdir = ERR_PTR(ret); + trace_cachefiles_lookup(NULL, dir, subdir); + if (IS_ERR(subdir)) { + trace_cachefiles_vfs_error(NULL, d_backing_inode(dir), + PTR_ERR(subdir), + cachefiles_trace_lookup_error); + if (PTR_ERR(subdir) == -ENOMEM) + goto nomem_d_alloc; + goto lookup_error; + } + + _debug("subdir -> %pd %s", + subdir, d_backing_inode(subdir) ? "positive" : "negative"); + + /* we need to create the subdir if it doesn't exist yet */ + if (d_is_negative(subdir)) { + ret = cachefiles_has_space(cache, 1, 0, + cachefiles_has_space_for_create); + if (ret < 0) + goto mkdir_error; + + _debug("attempt mkdir"); + + path.mnt = cache->mnt; + path.dentry = dir; + ret = security_path_mkdir(&path, subdir, 0700); + if (ret < 0) + goto mkdir_error; + ret = cachefiles_inject_write_error(); + if (ret == 0) { + subdir = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700, NULL); + if (IS_ERR(subdir)) + ret = PTR_ERR(subdir); + } else { + end_creating(subdir); + subdir = ERR_PTR(ret); + } + if (IS_ERR(subdir)) { + trace_cachefiles_vfs_error(NULL, d_inode(dir), ret, + cachefiles_trace_mkdir_error); + goto mkdir_error; + } + trace_cachefiles_mkdir(dir, subdir); + + if (unlikely(d_unhashed(subdir) || d_is_negative(subdir))) { + end_creating(subdir); + goto retry; + } + ASSERT(d_backing_inode(subdir)); + + _debug("mkdir -> %pd{ino=%llu}", + subdir, d_backing_inode(subdir)->i_ino); + if (_is_new) + *_is_new = true; + } + + /* Tell rmdir() it's not allowed to delete the subdir */ + inode_lock(d_inode(subdir)); + end_creating_keep(subdir); + + if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) { + pr_notice("cachefiles: Inode already in use: %pd (B=%llx)\n", + subdir, d_inode(subdir)->i_ino); + goto mark_error; + } + + inode_unlock(d_inode(subdir)); + + /* we need to make sure the subdir is a directory */ + ASSERT(d_backing_inode(subdir)); + + if (!d_can_lookup(subdir)) { + pr_err("%s is not a directory\n", dirname); + ret = -EIO; + goto check_error; + } + + ret = -EPERM; + if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) || + !d_backing_inode(subdir)->i_op->lookup || + !d_backing_inode(subdir)->i_op->mkdir || + !d_backing_inode(subdir)->i_op->rename || + !d_backing_inode(subdir)->i_op->rmdir || + !d_backing_inode(subdir)->i_op->unlink) + goto check_error; + + _leave(" = [%llu]", d_backing_inode(subdir)->i_ino); + return subdir; + +check_error: + cachefiles_put_directory(subdir); + _leave(" = %d [check]", ret); + return ERR_PTR(ret); + +mark_error: + inode_unlock(d_inode(subdir)); + dput(subdir); + return ERR_PTR(-EBUSY); + +mkdir_error: + end_creating(subdir); + pr_err("mkdir %s failed with error %d\n", dirname, ret); + return ERR_PTR(ret); + +lookup_error: + ret = PTR_ERR(subdir); + pr_err("Lookup %s failed with error %d\n", dirname, ret); + return ERR_PTR(ret); + +nomem_d_alloc: + _leave(" = -ENOMEM"); + return ERR_PTR(-ENOMEM); +} + +/* + * Put a subdirectory. + */ +void cachefiles_put_directory(struct dentry *dir) +{ + if (dir) { + cachefiles_do_unmark_inode_in_use(NULL, d_inode(dir)); + dput(dir); + } +} + +/* + * Remove a regular file from the cache. + */ +static int cachefiles_unlink(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dir, struct dentry *dentry, + enum fscache_why_object_killed why) +{ + struct path path = { + .mnt = cache->mnt, + .dentry = dir, + }; + int ret; + + trace_cachefiles_unlink(object, d_inode(dentry)->i_ino, why); + ret = security_path_unlink(&path, dentry); + if (ret < 0) { + cachefiles_io_error(cache, "Unlink security error"); + return ret; + } + + ret = cachefiles_inject_remove_error(); + if (ret == 0) { + ret = vfs_unlink(&nop_mnt_idmap, d_backing_inode(dir), dentry, NULL); + if (ret == -EIO) + cachefiles_io_error(cache, "Unlink failed"); + } + if (ret != 0) + trace_cachefiles_vfs_error(object, d_backing_inode(dir), ret, + cachefiles_trace_unlink_error); + return ret; +} + +/* + * Delete an object representation from the cache + * - File backed objects are unlinked + * - Directory backed objects are stuffed into the graveyard for userspace to + * delete + * On entry dir must be locked. It will be unlocked on exit. + * On entry there must be at least 2 refs on rep, one will be dropped on exit. + */ +int cachefiles_bury_object(struct cachefiles_cache *cache, + struct cachefiles_object *object, + struct dentry *dir, + struct dentry *rep, + enum fscache_why_object_killed why) +{ + struct dentry *grave; + struct renamedata rd = {}; + struct path path, path_to_graveyard; + char nbuffer[8 + 8 + 1]; + int ret; + + _enter(",'%pd','%pd'", dir, rep); + + if (rep->d_parent != dir) { + end_removing(rep); + _leave(" = -ESTALE"); + return -ESTALE; + } + + /* non-directories can just be unlinked */ + if (!d_is_dir(rep)) { + ret = cachefiles_unlink(cache, object, dir, rep, why); + end_removing(rep); + + _leave(" = %d", ret); + return ret; + } + + /* directories have to be moved to the graveyard */ + _debug("move stale object to graveyard"); + end_removing(rep); + +try_again: + /* first step is to make up a grave dentry in the graveyard */ + sprintf(nbuffer, "%08x%08x", + (uint32_t) ktime_get_real_seconds(), + (uint32_t) atomic_inc_return(&cache->gravecounter)); + + rd.mnt_idmap = &nop_mnt_idmap; + rd.old_parent = dir; + rd.new_parent = cache->graveyard; + rd.flags = 0; + ret = start_renaming_dentry(&rd, 0, rep, &QSTR(nbuffer)); + if (ret) { + /* Some errors aren't fatal */ + if (ret == -EXDEV) + /* double-lock failed */ + return ret; + if (d_unhashed(rep) || rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { + /* the entry was probably culled when we dropped the parent dir + * lock */ + _leave(" = 0 [culled?]"); + return 0; + } + if (ret == -EINVAL || ret == -ENOTEMPTY) { + cachefiles_io_error(cache, "May not make directory loop"); + return -EIO; + } + if (ret == -ENOMEM) { + _leave(" = -ENOMEM"); + return -ENOMEM; + } + + cachefiles_io_error(cache, "Lookup error %d", ret); + return -EIO; + } + + if (d_mountpoint(rep)) { + end_renaming(&rd); + cachefiles_io_error(cache, "Mountpoint in cache"); + return -EIO; + } + + grave = rd.new_dentry; + if (d_is_positive(grave)) { + end_renaming(&rd); + grave = NULL; + cond_resched(); + goto try_again; + } + + if (d_mountpoint(grave)) { + end_renaming(&rd); + cachefiles_io_error(cache, "Mountpoint in graveyard"); + return -EIO; + } + + /* attempt the rename */ + path.mnt = cache->mnt; + path.dentry = dir; + path_to_graveyard.mnt = cache->mnt; + path_to_graveyard.dentry = cache->graveyard; + ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0); + if (ret < 0) { + cachefiles_io_error(cache, "Rename security error %d", ret); + } else { + trace_cachefiles_rename(object, d_inode(rep)->i_ino, why); + ret = cachefiles_inject_read_error(); + if (ret == 0) + ret = vfs_rename(&rd); + if (ret != 0) + trace_cachefiles_vfs_error(object, d_inode(dir), ret, + cachefiles_trace_rename_error); + if (ret != 0 && ret != -ENOMEM) + cachefiles_io_error(cache, + "Rename failed with error %d", ret); + } + + cachefiles_do_unmark_inode_in_use(object, d_inode(rep)); + end_renaming(&rd); + _leave(" = 0"); + return 0; +} + +/* + * Delete a cache file. + */ +int cachefiles_delete_object(struct cachefiles_object *object, + enum fscache_why_object_killed why) +{ + struct cachefiles_volume *volume = object->volume; + struct dentry *dentry = object->file->f_path.dentry; + struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; + int ret; + + _enter(",OBJ%x{%pD}", object->debug_id, object->file); + + dentry = start_removing_dentry(fan, dentry); + if (IS_ERR(dentry)) + ret = PTR_ERR(dentry); + else + ret = cachefiles_unlink(volume->cache, object, fan, dentry, why); + end_removing(dentry); + return ret; +} + +/* + * Create a temporary file and leave it unattached and un-xattr'd until the + * time comes to discard the object from memory. + */ +struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) +{ + struct cachefiles_volume *volume = object->volume; + struct cachefiles_cache *cache = volume->cache; + const struct cred *saved_cred; + struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; + struct file *file; + const struct path parentpath = { .mnt = cache->mnt, .dentry = fan }; + uint64_t ni_size; + long ret; + + + cachefiles_begin_secure(cache, &saved_cred); + + ret = cachefiles_inject_write_error(); + if (ret == 0) { + file = kernel_tmpfile_open(&nop_mnt_idmap, &parentpath, + S_IFREG | 0600, + O_RDWR | O_LARGEFILE | O_DIRECT, + cache->cache_cred); + ret = PTR_ERR_OR_ZERO(file); + } + if (ret) { + trace_cachefiles_vfs_error(object, d_inode(fan), ret, + cachefiles_trace_tmpfile_error); + if (ret == -EIO) + cachefiles_io_error_obj(object, "Failed to create tmpfile"); + goto err; + } + + trace_cachefiles_tmpfile(object, file_inode(file)); + + /* This is a newly created file with no other possible user */ + if (!cachefiles_mark_inode_in_use(object, file_inode(file))) + WARN_ON(1); + + ni_size = object->cookie->object_size; + ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); + + if (ni_size > 0) { + trace_cachefiles_trunc(object, file_inode(file), 0, ni_size, + cachefiles_trunc_expand_tmpfile); + ret = cachefiles_inject_write_error(); + if (ret == 0) + ret = vfs_truncate(&file->f_path, ni_size); + if (ret < 0) { + trace_cachefiles_vfs_error( + object, file_inode(file), ret, + cachefiles_trace_trunc_error); + goto err_unuse; + } + } + + ret = -EINVAL; + if (unlikely(!file->f_op->read_iter) || + unlikely(!file->f_op->write_iter)) { + pr_notice("Cache does not support read_iter and write_iter\n"); + goto err_unuse; + } +out: + cachefiles_end_secure(cache, saved_cred); + return file; + +err_unuse: + cachefiles_do_unmark_inode_in_use(object, file_inode(file)); + fput(file); +err: + file = ERR_PTR(ret); + goto out; +} + +/* + * Create a new file. + */ +static bool cachefiles_create_file(struct cachefiles_object *object) +{ + struct file *file; + int ret; + + ret = cachefiles_has_space(object->volume->cache, 1, 0, + cachefiles_has_space_for_create); + if (ret < 0) + return false; + + file = cachefiles_create_tmpfile(object); + if (IS_ERR(file)) + return false; + + set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); + set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); + _debug("create -> %pD{ino=%llu}", file, file_inode(file)->i_ino); + object->file = file; + return true; +} + +/* + * Open an existing file, checking its attributes and replacing it if it is + * stale. + */ +static bool cachefiles_open_file(struct cachefiles_object *object, + struct dentry *dentry) +{ + struct cachefiles_cache *cache = object->volume->cache; + struct file *file; + struct path path; + int ret; + + _enter("%pd", dentry); + + if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) { + pr_notice("cachefiles: Inode already in use: %pd (B=%llx)\n", + dentry, d_inode(dentry)->i_ino); + return false; + } + + /* We need to open a file interface onto a data file now as we can't do + * it on demand because writeback called from do_exit() sees + * current->fs == NULL - which breaks d_path() called from ext4 open. + */ + path.mnt = cache->mnt; + path.dentry = dentry; + file = kernel_file_open(&path, O_RDWR | O_LARGEFILE | O_DIRECT, cache->cache_cred); + if (IS_ERR(file)) { + trace_cachefiles_vfs_error(object, d_backing_inode(dentry), + PTR_ERR(file), + cachefiles_trace_open_error); + goto error; + } + + if (unlikely(!file->f_op->read_iter) || + unlikely(!file->f_op->write_iter)) { + pr_notice("Cache does not support read_iter and write_iter\n"); + goto error_fput; + } + _debug("file -> %pd positive", dentry); + + ret = cachefiles_check_auxdata(object, file); + if (ret < 0) + goto check_failed; + + clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags); + + object->file = file; + + /* Always update the atime on an object we've just looked up (this is + * used to keep track of culling, and atimes are only updated by read, + * write and readdir but not lookup or open). + */ + touch_atime(&file->f_path); + return true; + +check_failed: + fscache_cookie_lookup_negative(object->cookie); + cachefiles_unmark_inode_in_use(object, file); + fput(file); + if (ret == -ESTALE) + return cachefiles_create_file(object); + return false; + +error_fput: + fput(file); +error: + cachefiles_do_unmark_inode_in_use(object, d_inode(dentry)); + return false; +} + +/* + * walk from the parent object to the child object through the backing + * filesystem, creating directories as we go + */ +bool cachefiles_look_up_object(struct cachefiles_object *object) +{ + struct cachefiles_volume *volume = object->volume; + struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; + int ret; + + _enter("OBJ%x,%s,", object->debug_id, object->d_name); + + /* Look up path "cache/vol/fanout/file". */ + ret = cachefiles_inject_read_error(); + if (ret == 0) + dentry = lookup_one_positive_unlocked(&nop_mnt_idmap, + &QSTR(object->d_name), fan); + else + dentry = ERR_PTR(ret); + trace_cachefiles_lookup(object, fan, dentry); + if (IS_ERR(dentry)) { + if (dentry == ERR_PTR(-ENOENT)) + goto new_file; + if (dentry == ERR_PTR(-EIO)) + cachefiles_io_error_obj(object, "Lookup failed"); + return false; + } + + if (!d_is_reg(dentry)) { + pr_err("%pd is not a file\n", dentry); + struct dentry *de = start_removing_dentry(fan, dentry); + if (IS_ERR(de)) + ret = PTR_ERR(de); + else + ret = cachefiles_bury_object(volume->cache, object, + fan, de, + FSCACHE_OBJECT_IS_WEIRD); + dput(dentry); + if (ret < 0) + return false; + goto new_file; + } + + ret = cachefiles_open_file(object, dentry); + dput(dentry); + if (!ret) + return false; + + _leave(" = t [%llu]", file_inode(object->file)->i_ino); + return true; + +new_file: + fscache_cookie_lookup_negative(object->cookie); + return cachefiles_create_file(object); +} + +/* + * Attempt to link a temporary file into its rightful place in the cache. + */ +bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache, + struct cachefiles_object *object) +{ + struct cachefiles_volume *volume = object->volume; + struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; + bool success = false; + int ret; + + _enter(",%pD", object->file); + + ret = cachefiles_inject_read_error(); + if (ret == 0) + dentry = start_creating(&nop_mnt_idmap, fan, &QSTR(object->d_name)); + else + dentry = ERR_PTR(ret); + if (IS_ERR(dentry)) { + trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), + cachefiles_trace_lookup_error); + _debug("lookup fail %ld", PTR_ERR(dentry)); + goto out; + } + + /* + * This loop will only execute more than once if some other thread + * races to create the object we are trying to create. + */ + while (!d_is_negative(dentry)) { + ret = cachefiles_unlink(volume->cache, object, fan, dentry, + FSCACHE_OBJECT_IS_STALE); + if (ret < 0) + goto out_end; + + end_creating(dentry); + + ret = cachefiles_inject_read_error(); + if (ret == 0) + dentry = start_creating(&nop_mnt_idmap, fan, + &QSTR(object->d_name)); + else + dentry = ERR_PTR(ret); + if (IS_ERR(dentry)) { + trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), + cachefiles_trace_lookup_error); + _debug("lookup fail %ld", PTR_ERR(dentry)); + goto out; + } + } + + ret = cachefiles_inject_read_error(); + if (ret == 0) + ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap, + d_inode(fan), dentry, NULL); + if (ret < 0) { + trace_cachefiles_vfs_error(object, d_inode(fan), ret, + cachefiles_trace_link_error); + _debug("link fail %d", ret); + } else { + trace_cachefiles_link(object, file_inode(object->file)); + spin_lock(&object->lock); + /* TODO: Do we want to switch the file pointer to the new dentry? */ + clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); + spin_unlock(&object->lock); + success = true; + } + +out_end: + end_creating(dentry); +out: + _leave(" = %u", success); + return success; +} + +/* + * Look up an inode to be checked or culled. Return -EBUSY if the inode is + * marked in use. + */ +static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, + struct dentry *dir, + char *filename) +{ + struct dentry *victim; + int ret = -ENOENT; + + victim = start_removing(&nop_mnt_idmap, dir, &QSTR(filename)); + + if (IS_ERR(victim)) + goto lookup_error; + if (d_inode(victim)->i_flags & S_KERNEL_FILE) + goto lookup_busy; + return victim; + +lookup_busy: + ret = -EBUSY; + end_removing(victim); + return ERR_PTR(ret); + +lookup_error: + ret = PTR_ERR(victim); + if (ret == -ENOENT) + return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ + + if (ret == -EIO) { + cachefiles_io_error(cache, "Lookup failed"); + } else if (ret != -ENOMEM) { + pr_err("Internal error: %d\n", ret); + ret = -EIO; + } + + return ERR_PTR(ret); +} + +/* + * Cull an object if it's not in use + * - called only by cache manager daemon + */ +int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, + char *filename) +{ + struct dentry *victim; + struct inode *inode; + int ret; + + _enter(",%pd/,%s", dir, filename); + + victim = cachefiles_lookup_for_cull(cache, dir, filename); + if (IS_ERR(victim)) + return PTR_ERR(victim); + + /* check to see if someone is using this object */ + inode = d_inode(victim); + inode_lock(inode); + if (inode->i_flags & S_KERNEL_FILE) { + ret = -EBUSY; + } else { + /* Stop the cache from picking it back up */ + inode->i_flags |= S_KERNEL_FILE; + ret = 0; + } + inode_unlock(inode); + if (ret < 0) + goto error_unlock; + + /* + * cachefiles_bury_object() expects 2 references to 'victim', + * and drops one. + */ + dget(victim); + ret = cachefiles_bury_object(cache, NULL, dir, victim, + FSCACHE_OBJECT_WAS_CULLED); + dput(victim); + if (ret < 0) + goto error; + + fscache_count_culled(); + _leave(" = 0"); + return 0; + +error_unlock: + end_removing(victim); +error: + if (ret == -ENOENT) + return -ESTALE; /* Probably got retired by the netfs */ + + if (ret != -ENOMEM) { + pr_err("Internal error: %d\n", ret); + ret = -EIO; + } + + _leave(" = %d", ret); + return ret; +} + +/* + * Find out if an object is in use or not + * - called only by cache manager daemon + * - returns -EBUSY or 0 to indicate whether an object is in use or not + */ +int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, + char *filename) +{ + struct dentry *victim; + int ret = 0; + + victim = cachefiles_lookup_for_cull(cache, dir, filename); + if (IS_ERR(victim)) + return PTR_ERR(victim); + + inode_unlock(d_inode(dir)); + dput(victim); + return ret; +} |