diff options
Diffstat (limited to 'fs/cachefiles/io.c')
| -rw-r--r-- | fs/cachefiles/io.c | 651 |
1 files changed, 651 insertions, 0 deletions
diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c new file mode 100644 index 000000000000..000a28f46e59 --- /dev/null +++ b/fs/cachefiles/io.c @@ -0,0 +1,651 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* kiocb-using read/write + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/mount.h> +#include <linux/slab.h> +#include <linux/file.h> +#include <linux/uio.h> +#include <linux/falloc.h> +#include <linux/sched/mm.h> +#include <trace/events/fscache.h> +#include "internal.h" + +struct cachefiles_kiocb { + struct kiocb iocb; + refcount_t ki_refcnt; + loff_t start; + union { + size_t skipped; + size_t len; + }; + struct cachefiles_object *object; + netfs_io_terminated_t term_func; + void *term_func_priv; + bool was_async; + unsigned int inval_counter; /* Copy of cookie->inval_counter */ + u64 b_writing; +}; + +static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki) +{ + if (refcount_dec_and_test(&ki->ki_refcnt)) { + cachefiles_put_object(ki->object, cachefiles_obj_put_ioreq); + fput(ki->iocb.ki_filp); + kfree(ki); + } +} + +/* + * Handle completion of a read from the cache. + */ +static void cachefiles_read_complete(struct kiocb *iocb, long ret) +{ + struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb); + struct inode *inode = file_inode(ki->iocb.ki_filp); + + _enter("%ld", ret); + + if (ret < 0) + trace_cachefiles_io_error(ki->object, inode, ret, + cachefiles_trace_read_error); + + if (ki->term_func) { + if (ret >= 0) { + if (ki->object->cookie->inval_counter == ki->inval_counter) + ki->skipped += ret; + else + ret = -ESTALE; + } + + ki->term_func(ki->term_func_priv, ret, ki->was_async); + } + + cachefiles_put_kiocb(ki); +} + +/* + * Initiate a read from the cache. + */ +static int cachefiles_read(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + enum netfs_read_from_hole read_hole, + netfs_io_terminated_t term_func, + void *term_func_priv) +{ + struct cachefiles_object *object; + struct cachefiles_kiocb *ki; + struct file *file; + unsigned int old_nofs; + ssize_t ret = -ENOBUFS; + size_t len = iov_iter_count(iter), skipped = 0; + + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ)) + goto presubmission_error; + + fscache_count_read(); + object = cachefiles_cres_object(cres); + file = cachefiles_cres_file(cres); + + _enter("%pD,%li,%llx,%zx/%llx", + file, file_inode(file)->i_ino, start_pos, len, + i_size_read(file_inode(file))); + + /* If the caller asked us to seek for data before doing the read, then + * we should do that now. If we find a gap, we fill it with zeros. + */ + if (read_hole != NETFS_READ_HOLE_IGNORE) { + loff_t off = start_pos, off2; + + off2 = cachefiles_inject_read_error(); + if (off2 == 0) + off2 = vfs_llseek(file, off, SEEK_DATA); + if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) { + skipped = 0; + ret = off2; + goto presubmission_error; + } + + if (off2 == -ENXIO || off2 >= start_pos + len) { + /* The region is beyond the EOF or there's no more data + * in the region, so clear the rest of the buffer and + * return success. + */ + ret = -ENODATA; + if (read_hole == NETFS_READ_HOLE_FAIL) + goto presubmission_error; + + iov_iter_zero(len, iter); + skipped = len; + ret = 0; + goto presubmission_error; + } + + skipped = off2 - off; + iov_iter_zero(skipped, iter); + } + + ret = -ENOMEM; + ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL); + if (!ki) + goto presubmission_error; + + refcount_set(&ki->ki_refcnt, 2); + ki->iocb.ki_filp = file; + ki->iocb.ki_pos = start_pos + skipped; + ki->iocb.ki_flags = IOCB_DIRECT; + ki->iocb.ki_ioprio = get_current_ioprio(); + ki->skipped = skipped; + ki->object = object; + ki->inval_counter = cres->inval_counter; + ki->term_func = term_func; + ki->term_func_priv = term_func_priv; + ki->was_async = true; + + if (ki->term_func) + ki->iocb.ki_complete = cachefiles_read_complete; + + get_file(ki->iocb.ki_filp); + cachefiles_grab_object(object, cachefiles_obj_get_ioreq); + + trace_cachefiles_read(object, file_inode(file), ki->iocb.ki_pos, len - skipped); + old_nofs = memalloc_nofs_save(); + ret = cachefiles_inject_read_error(); + if (ret == 0) + ret = vfs_iocb_iter_read(file, &ki->iocb, iter); + memalloc_nofs_restore(old_nofs); + switch (ret) { + case -EIOCBQUEUED: + goto in_progress; + + case -ERESTARTSYS: + case -ERESTARTNOINTR: + case -ERESTARTNOHAND: + case -ERESTART_RESTARTBLOCK: + /* There's no easy way to restart the syscall since other AIO's + * may be already running. Just fail this IO with EINTR. + */ + ret = -EINTR; + fallthrough; + default: + ki->was_async = false; + cachefiles_read_complete(&ki->iocb, ret); + if (ret > 0) + ret = 0; + break; + } + +in_progress: + cachefiles_put_kiocb(ki); + _leave(" = %zd", ret); + return ret; + +presubmission_error: + if (term_func) + term_func(term_func_priv, ret < 0 ? ret : skipped, false); + return ret; +} + +/* + * Query the occupancy of the cache in a region, returning where the next chunk + * of data starts and how long it is. + */ +static int cachefiles_query_occupancy(struct netfs_cache_resources *cres, + loff_t start, size_t len, size_t granularity, + loff_t *_data_start, size_t *_data_len) +{ + struct cachefiles_object *object; + struct file *file; + loff_t off, off2; + + *_data_start = -1; + *_data_len = 0; + + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ)) + return -ENOBUFS; + + object = cachefiles_cres_object(cres); + file = cachefiles_cres_file(cres); + granularity = max_t(size_t, object->volume->cache->bsize, granularity); + + _enter("%pD,%li,%llx,%zx/%llx", + file, file_inode(file)->i_ino, start, len, + i_size_read(file_inode(file))); + + off = cachefiles_inject_read_error(); + if (off == 0) + off = vfs_llseek(file, start, SEEK_DATA); + if (off == -ENXIO) + return -ENODATA; /* Beyond EOF */ + if (off < 0 && off >= (loff_t)-MAX_ERRNO) + return -ENOBUFS; /* Error. */ + if (round_up(off, granularity) >= start + len) + return -ENODATA; /* No data in range */ + + off2 = cachefiles_inject_read_error(); + if (off2 == 0) + off2 = vfs_llseek(file, off, SEEK_HOLE); + if (off2 == -ENXIO) + return -ENODATA; /* Beyond EOF */ + if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO) + return -ENOBUFS; /* Error. */ + + /* Round away partial blocks */ + off = round_up(off, granularity); + off2 = round_down(off2, granularity); + if (off2 <= off) + return -ENODATA; + + *_data_start = off; + if (off2 > start + len) + *_data_len = len; + else + *_data_len = off2 - off; + return 0; +} + +/* + * Handle completion of a write to the cache. + */ +static void cachefiles_write_complete(struct kiocb *iocb, long ret) +{ + struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb); + struct cachefiles_object *object = ki->object; + struct inode *inode = file_inode(ki->iocb.ki_filp); + + _enter("%ld", ret); + + /* Tell lockdep we inherited freeze protection from submission thread */ + __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE); + __sb_end_write(inode->i_sb, SB_FREEZE_WRITE); + + if (ret < 0) + trace_cachefiles_io_error(object, inode, ret, + cachefiles_trace_write_error); + + atomic_long_sub(ki->b_writing, &object->volume->cache->b_writing); + set_bit(FSCACHE_COOKIE_HAVE_DATA, &object->cookie->flags); + if (ki->term_func) + ki->term_func(ki->term_func_priv, ret, ki->was_async); + cachefiles_put_kiocb(ki); +} + +/* + * Initiate a write to the cache. + */ +int __cachefiles_write(struct cachefiles_object *object, + struct file *file, + loff_t start_pos, + struct iov_iter *iter, + netfs_io_terminated_t term_func, + void *term_func_priv) +{ + struct cachefiles_cache *cache; + struct cachefiles_kiocb *ki; + struct inode *inode; + unsigned int old_nofs; + ssize_t ret; + size_t len = iov_iter_count(iter); + + fscache_count_write(); + cache = object->volume->cache; + + _enter("%pD,%li,%llx,%zx/%llx", + file, file_inode(file)->i_ino, start_pos, len, + i_size_read(file_inode(file))); + + ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL); + if (!ki) { + if (term_func) + term_func(term_func_priv, -ENOMEM, false); + return -ENOMEM; + } + + refcount_set(&ki->ki_refcnt, 2); + ki->iocb.ki_filp = file; + ki->iocb.ki_pos = start_pos; + ki->iocb.ki_flags = IOCB_DIRECT | IOCB_WRITE; + ki->iocb.ki_ioprio = get_current_ioprio(); + ki->object = object; + ki->start = start_pos; + ki->len = len; + ki->term_func = term_func; + ki->term_func_priv = term_func_priv; + ki->was_async = true; + ki->b_writing = (len + (1 << cache->bshift) - 1) >> cache->bshift; + + if (ki->term_func) + ki->iocb.ki_complete = cachefiles_write_complete; + atomic_long_add(ki->b_writing, &cache->b_writing); + + /* Open-code file_start_write here to grab freeze protection, which + * will be released by another thread in aio_complete_rw(). Fool + * lockdep by telling it the lock got released so that it doesn't + * complain about the held lock when we return to userspace. + */ + inode = file_inode(file); + __sb_start_write(inode->i_sb, SB_FREEZE_WRITE); + __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE); + + get_file(ki->iocb.ki_filp); + cachefiles_grab_object(object, cachefiles_obj_get_ioreq); + + trace_cachefiles_write(object, inode, ki->iocb.ki_pos, len); + old_nofs = memalloc_nofs_save(); + ret = cachefiles_inject_write_error(); + if (ret == 0) + ret = vfs_iocb_iter_write(file, &ki->iocb, iter); + memalloc_nofs_restore(old_nofs); + switch (ret) { + case -EIOCBQUEUED: + goto in_progress; + + case -ERESTARTSYS: + case -ERESTARTNOINTR: + case -ERESTARTNOHAND: + case -ERESTART_RESTARTBLOCK: + /* There's no easy way to restart the syscall since other AIO's + * may be already running. Just fail this IO with EINTR. + */ + ret = -EINTR; + fallthrough; + default: + ki->was_async = false; + cachefiles_write_complete(&ki->iocb, ret); + if (ret > 0) + ret = 0; + break; + } + +in_progress: + cachefiles_put_kiocb(ki); + _leave(" = %zd", ret); + return ret; +} + +static int cachefiles_write(struct netfs_cache_resources *cres, + loff_t start_pos, + struct iov_iter *iter, + netfs_io_terminated_t term_func, + void *term_func_priv) +{ + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) { + if (term_func) + term_func(term_func_priv, -ENOBUFS, false); + return -ENOBUFS; + } + + return __cachefiles_write(cachefiles_cres_object(cres), + cachefiles_cres_file(cres), + start_pos, iter, + term_func, term_func_priv); +} + +/* + * Prepare a read operation, shortening it to a cached/uncached + * boundary as appropriate. + */ +static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq, + loff_t i_size) +{ + enum cachefiles_prepare_read_trace why; + struct netfs_io_request *rreq = subreq->rreq; + struct netfs_cache_resources *cres = &rreq->cache_resources; + struct cachefiles_object *object; + struct cachefiles_cache *cache; + struct fscache_cookie *cookie = fscache_cres_cookie(cres); + const struct cred *saved_cred; + struct file *file = cachefiles_cres_file(cres); + enum netfs_io_source ret = NETFS_DOWNLOAD_FROM_SERVER; + loff_t off, to; + ino_t ino = file ? file_inode(file)->i_ino : 0; + int rc; + + _enter("%zx @%llx/%llx", subreq->len, subreq->start, i_size); + + if (subreq->start >= i_size) { + ret = NETFS_FILL_WITH_ZEROES; + why = cachefiles_trace_read_after_eof; + goto out_no_object; + } + + if (test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) { + __set_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags); + why = cachefiles_trace_read_no_data; + if (!test_bit(NETFS_SREQ_ONDEMAND, &subreq->flags)) + goto out_no_object; + } + + /* The object and the file may be being created in the background. */ + if (!file) { + why = cachefiles_trace_read_no_file; + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ)) + goto out_no_object; + file = cachefiles_cres_file(cres); + if (!file) + goto out_no_object; + ino = file_inode(file)->i_ino; + } + + object = cachefiles_cres_object(cres); + cache = object->volume->cache; + cachefiles_begin_secure(cache, &saved_cred); +retry: + off = cachefiles_inject_read_error(); + if (off == 0) + off = vfs_llseek(file, subreq->start, SEEK_DATA); + if (off < 0 && off >= (loff_t)-MAX_ERRNO) { + if (off == (loff_t)-ENXIO) { + why = cachefiles_trace_read_seek_nxio; + goto download_and_store; + } + trace_cachefiles_io_error(object, file_inode(file), off, + cachefiles_trace_seek_error); + why = cachefiles_trace_read_seek_error; + goto out; + } + + if (off >= subreq->start + subreq->len) { + why = cachefiles_trace_read_found_hole; + goto download_and_store; + } + + if (off > subreq->start) { + off = round_up(off, cache->bsize); + subreq->len = off - subreq->start; + why = cachefiles_trace_read_found_part; + goto download_and_store; + } + + to = cachefiles_inject_read_error(); + if (to == 0) + to = vfs_llseek(file, subreq->start, SEEK_HOLE); + if (to < 0 && to >= (loff_t)-MAX_ERRNO) { + trace_cachefiles_io_error(object, file_inode(file), to, + cachefiles_trace_seek_error); + why = cachefiles_trace_read_seek_error; + goto out; + } + + if (to < subreq->start + subreq->len) { + if (subreq->start + subreq->len >= i_size) + to = round_up(to, cache->bsize); + else + to = round_down(to, cache->bsize); + subreq->len = to - subreq->start; + } + + why = cachefiles_trace_read_have_data; + ret = NETFS_READ_FROM_CACHE; + goto out; + +download_and_store: + __set_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags); + if (test_bit(NETFS_SREQ_ONDEMAND, &subreq->flags)) { + rc = cachefiles_ondemand_read(object, subreq->start, + subreq->len); + if (!rc) { + __clear_bit(NETFS_SREQ_ONDEMAND, &subreq->flags); + goto retry; + } + ret = NETFS_INVALID_READ; + } +out: + cachefiles_end_secure(cache, saved_cred); +out_no_object: + trace_cachefiles_prep_read(subreq, ret, why, ino); + return ret; +} + +/* + * Prepare for a write to occur. + */ +int __cachefiles_prepare_write(struct cachefiles_object *object, + struct file *file, + loff_t *_start, size_t *_len, + bool no_space_allocated_yet) +{ + struct cachefiles_cache *cache = object->volume->cache; + loff_t start = *_start, pos; + size_t len = *_len, down; + int ret; + + /* Round to DIO size */ + down = start - round_down(start, PAGE_SIZE); + *_start = start - down; + *_len = round_up(down + len, PAGE_SIZE); + + /* We need to work out whether there's sufficient disk space to perform + * the write - but we can skip that check if we have space already + * allocated. + */ + if (no_space_allocated_yet) + goto check_space; + + pos = cachefiles_inject_read_error(); + if (pos == 0) + pos = vfs_llseek(file, *_start, SEEK_DATA); + if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) { + if (pos == -ENXIO) + goto check_space; /* Unallocated tail */ + trace_cachefiles_io_error(object, file_inode(file), pos, + cachefiles_trace_seek_error); + return pos; + } + if ((u64)pos >= (u64)*_start + *_len) + goto check_space; /* Unallocated region */ + + /* We have a block that's at least partially filled - if we're low on + * space, we need to see if it's fully allocated. If it's not, we may + * want to cull it. + */ + if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE, + cachefiles_has_space_check) == 0) + return 0; /* Enough space to simply overwrite the whole block */ + + pos = cachefiles_inject_read_error(); + if (pos == 0) + pos = vfs_llseek(file, *_start, SEEK_HOLE); + if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) { + trace_cachefiles_io_error(object, file_inode(file), pos, + cachefiles_trace_seek_error); + return pos; + } + if ((u64)pos >= (u64)*_start + *_len) + return 0; /* Fully allocated */ + + /* Partially allocated, but insufficient space: cull. */ + fscache_count_no_write_space(); + ret = cachefiles_inject_remove_error(); + if (ret == 0) + ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + *_start, *_len); + if (ret < 0) { + trace_cachefiles_io_error(object, file_inode(file), ret, + cachefiles_trace_fallocate_error); + cachefiles_io_error_obj(object, + "CacheFiles: fallocate failed (%d)\n", ret); + ret = -EIO; + } + + return ret; + +check_space: + return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE, + cachefiles_has_space_for_write); +} + +static int cachefiles_prepare_write(struct netfs_cache_resources *cres, + loff_t *_start, size_t *_len, loff_t i_size, + bool no_space_allocated_yet) +{ + struct cachefiles_object *object = cachefiles_cres_object(cres); + struct cachefiles_cache *cache = object->volume->cache; + const struct cred *saved_cred; + int ret; + + if (!cachefiles_cres_file(cres)) { + if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) + return -ENOBUFS; + if (!cachefiles_cres_file(cres)) + return -ENOBUFS; + } + + cachefiles_begin_secure(cache, &saved_cred); + ret = __cachefiles_prepare_write(object, cachefiles_cres_file(cres), + _start, _len, + no_space_allocated_yet); + cachefiles_end_secure(cache, saved_cred); + return ret; +} + +/* + * Clean up an operation. + */ +static void cachefiles_end_operation(struct netfs_cache_resources *cres) +{ + struct file *file = cachefiles_cres_file(cres); + + if (file) + fput(file); + fscache_end_cookie_access(fscache_cres_cookie(cres), fscache_access_io_end); +} + +static const struct netfs_cache_ops cachefiles_netfs_cache_ops = { + .end_operation = cachefiles_end_operation, + .read = cachefiles_read, + .write = cachefiles_write, + .prepare_read = cachefiles_prepare_read, + .prepare_write = cachefiles_prepare_write, + .query_occupancy = cachefiles_query_occupancy, +}; + +/* + * Open the cache file when beginning a cache operation. + */ +bool cachefiles_begin_operation(struct netfs_cache_resources *cres, + enum fscache_want_state want_state) +{ + struct cachefiles_object *object = cachefiles_cres_object(cres); + + if (!cachefiles_cres_file(cres)) { + cres->ops = &cachefiles_netfs_cache_ops; + if (object->file) { + spin_lock(&object->lock); + if (!cres->cache_priv2 && object->file) + cres->cache_priv2 = get_file(object->file); + spin_unlock(&object->lock); + } + } + + if (!cachefiles_cres_file(cres) && want_state != FSCACHE_WANT_PARAMS) { + pr_err("failed to get cres->file\n"); + return false; + } + + return true; +} |