diff options
Diffstat (limited to 'fs/afs/write.c')
| -rw-r--r-- | fs/afs/write.c | 868 |
1 files changed, 868 insertions, 0 deletions
diff --git a/fs/afs/write.c b/fs/afs/write.c new file mode 100644 index 000000000..ec8d27cf9 --- /dev/null +++ b/fs/afs/write.c @@ -0,0 +1,868 @@ +/* handling of writes to regular files and writing back to the server + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/backing-dev.h> +#include <linux/slab.h> +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/writeback.h> +#include <linux/pagevec.h> +#include "internal.h" + +/* + * mark a page as having been made dirty and thus needing writeback + */ +int afs_set_page_dirty(struct page *page) +{ + _enter(""); + return __set_page_dirty_nobuffers(page); +} + +/* + * partly or wholly fill a page that's under preparation for writing + */ +static int afs_fill_page(struct afs_vnode *vnode, struct key *key, + loff_t pos, unsigned int len, struct page *page) +{ + struct afs_read *req; + int ret; + + _enter(",,%llu", (unsigned long long)pos); + + req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *), + GFP_KERNEL); + if (!req) + return -ENOMEM; + + refcount_set(&req->usage, 1); + req->pos = pos; + req->len = len; + req->nr_pages = 1; + req->pages = req->array; + req->pages[0] = page; + get_page(page); + + ret = afs_fetch_data(vnode, key, req); + afs_put_read(req); + if (ret < 0) { + if (ret == -ENOENT) { + _debug("got NOENT from server" + " - marking file deleted and stale"); + set_bit(AFS_VNODE_DELETED, &vnode->flags); + ret = -ESTALE; + } + } + + _leave(" = %d", ret); + return ret; +} + +/* + * prepare to perform part of a write to a page + */ +int afs_write_begin(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata) +{ + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); + struct page *page; + struct key *key = afs_file_key(file); + unsigned long priv; + unsigned f, from = pos & (PAGE_SIZE - 1); + unsigned t, to = from + len; + pgoff_t index = pos >> PAGE_SHIFT; + int ret; + + _enter("{%x:%u},{%lx},%u,%u", + vnode->fid.vid, vnode->fid.vnode, index, from, to); + + /* We want to store information about how much of a page is altered in + * page->private. + */ + BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8); + + page = grab_cache_page_write_begin(mapping, index, flags); + if (!page) + return -ENOMEM; + + if (!PageUptodate(page) && len != PAGE_SIZE) { + ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page); + if (ret < 0) { + unlock_page(page); + put_page(page); + _leave(" = %d [prep]", ret); + return ret; + } + SetPageUptodate(page); + } + + /* page won't leak in error case: it eventually gets cleaned off LRU */ + *pagep = page; + +try_again: + /* See if this page is already partially written in a way that we can + * merge the new write with. + */ + t = f = 0; + if (PagePrivate(page)) { + priv = page_private(page); + f = priv & AFS_PRIV_MAX; + t = priv >> AFS_PRIV_SHIFT; + ASSERTCMP(f, <=, t); + } + + if (f != t) { + if (PageWriteback(page)) { + trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), + page->index, priv); + goto flush_conflicting_write; + } + /* If the file is being filled locally, allow inter-write + * spaces to be merged into writes. If it's not, only write + * back what the user gives us. + */ + if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) && + (to < f || from > t)) + goto flush_conflicting_write; + if (from < f) + f = from; + if (to > t) + t = to; + } else { + f = from; + t = to; + } + + priv = (unsigned long)t << AFS_PRIV_SHIFT; + priv |= f; + trace_afs_page_dirty(vnode, tracepoint_string("begin"), + page->index, priv); + SetPagePrivate(page); + set_page_private(page, priv); + _leave(" = 0"); + return 0; + + /* The previous write and this write aren't adjacent or overlapping, so + * flush the page out. + */ +flush_conflicting_write: + _debug("flush conflict"); + ret = write_one_page(page); + if (ret < 0) { + _leave(" = %d", ret); + return ret; + } + + ret = lock_page_killable(page); + if (ret < 0) { + _leave(" = %d", ret); + return ret; + } + goto try_again; +} + +/* + * finalise part of a write to a page + */ +int afs_write_end(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct page *page, void *fsdata) +{ + struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); + struct key *key = afs_file_key(file); + loff_t i_size, maybe_i_size; + int ret; + + _enter("{%x:%u},{%lx}", + vnode->fid.vid, vnode->fid.vnode, page->index); + + maybe_i_size = pos + copied; + + i_size = i_size_read(&vnode->vfs_inode); + if (maybe_i_size > i_size) { + write_seqlock(&vnode->cb_lock); + i_size = i_size_read(&vnode->vfs_inode); + if (maybe_i_size > i_size) + i_size_write(&vnode->vfs_inode, maybe_i_size); + write_sequnlock(&vnode->cb_lock); + } + + if (!PageUptodate(page)) { + if (copied < len) { + /* Try and load any missing data from the server. The + * unmarshalling routine will take care of clearing any + * bits that are beyond the EOF. + */ + ret = afs_fill_page(vnode, key, pos + copied, + len - copied, page); + if (ret < 0) + goto out; + } + SetPageUptodate(page); + } + + set_page_dirty(page); + if (PageDirty(page)) + _debug("dirtied"); + ret = copied; + +out: + unlock_page(page); + put_page(page); + return ret; +} + +/* + * kill all the pages in the given range + */ +static void afs_kill_pages(struct address_space *mapping, + pgoff_t first, pgoff_t last) +{ + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + struct pagevec pv; + unsigned count, loop; + + _enter("{%x:%u},%lx-%lx", + vnode->fid.vid, vnode->fid.vnode, first, last); + + pagevec_init(&pv); + + do { + _debug("kill %lx-%lx", first, last); + + count = last - first + 1; + if (count > PAGEVEC_SIZE) + count = PAGEVEC_SIZE; + pv.nr = find_get_pages_contig(mapping, first, count, pv.pages); + ASSERTCMP(pv.nr, ==, count); + + for (loop = 0; loop < count; loop++) { + struct page *page = pv.pages[loop]; + ClearPageUptodate(page); + SetPageError(page); + end_page_writeback(page); + if (page->index >= first) + first = page->index + 1; + lock_page(page); + generic_error_remove_page(mapping, page); + unlock_page(page); + } + + __pagevec_release(&pv); + } while (first <= last); + + _leave(""); +} + +/* + * Redirty all the pages in a given range. + */ +static void afs_redirty_pages(struct writeback_control *wbc, + struct address_space *mapping, + pgoff_t first, pgoff_t last) +{ + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + struct pagevec pv; + unsigned count, loop; + + _enter("{%x:%u},%lx-%lx", + vnode->fid.vid, vnode->fid.vnode, first, last); + + pagevec_init(&pv); + + do { + _debug("redirty %lx-%lx", first, last); + + count = last - first + 1; + if (count > PAGEVEC_SIZE) + count = PAGEVEC_SIZE; + pv.nr = find_get_pages_contig(mapping, first, count, pv.pages); + ASSERTCMP(pv.nr, ==, count); + + for (loop = 0; loop < count; loop++) { + struct page *page = pv.pages[loop]; + + redirty_page_for_writepage(wbc, page); + end_page_writeback(page); + if (page->index >= first) + first = page->index + 1; + } + + __pagevec_release(&pv); + } while (first <= last); + + _leave(""); +} + +/* + * write to a file + */ +static int afs_store_data(struct address_space *mapping, + pgoff_t first, pgoff_t last, + unsigned offset, unsigned to) +{ + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + struct afs_fs_cursor fc; + struct afs_wb_key *wbk = NULL; + struct list_head *p; + int ret = -ENOKEY, ret2; + + _enter("%s{%x:%u.%u},%lx,%lx,%x,%x", + vnode->volume->name, + vnode->fid.vid, + vnode->fid.vnode, + vnode->fid.unique, + first, last, offset, to); + + spin_lock(&vnode->wb_lock); + p = vnode->wb_keys.next; + + /* Iterate through the list looking for a valid key to use. */ +try_next_key: + while (p != &vnode->wb_keys) { + wbk = list_entry(p, struct afs_wb_key, vnode_link); + _debug("wbk %u", key_serial(wbk->key)); + ret2 = key_validate(wbk->key); + if (ret2 == 0) + goto found_key; + if (ret == -ENOKEY) + ret = ret2; + p = p->next; + } + + spin_unlock(&vnode->wb_lock); + afs_put_wb_key(wbk); + _leave(" = %d [no keys]", ret); + return ret; + +found_key: + refcount_inc(&wbk->usage); + spin_unlock(&vnode->wb_lock); + + _debug("USE WB KEY %u", key_serial(wbk->key)); + + ret = -ERESTARTSYS; + if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) { + while (afs_select_fileserver(&fc)) { + fc.cb_break = afs_calc_vnode_cb_break(vnode); + afs_fs_store_data(&fc, mapping, first, last, offset, to); + } + + afs_check_for_remote_deletion(&fc, fc.vnode); + afs_vnode_commit_status(&fc, vnode, fc.cb_break); + ret = afs_end_vnode_operation(&fc); + } + + switch (ret) { + case 0: + afs_stat_v(vnode, n_stores); + atomic_long_add((last * PAGE_SIZE + to) - + (first * PAGE_SIZE + offset), + &afs_v2net(vnode)->n_store_bytes); + break; + case -EACCES: + case -EPERM: + case -ENOKEY: + case -EKEYEXPIRED: + case -EKEYREJECTED: + case -EKEYREVOKED: + _debug("next"); + spin_lock(&vnode->wb_lock); + p = wbk->vnode_link.next; + afs_put_wb_key(wbk); + goto try_next_key; + } + + afs_put_wb_key(wbk); + _leave(" = %d", ret); + return ret; +} + +/* + * Synchronously write back the locked page and any subsequent non-locked dirty + * pages. + */ +static int afs_write_back_from_locked_page(struct address_space *mapping, + struct writeback_control *wbc, + struct page *primary_page, + pgoff_t final_page) +{ + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + struct page *pages[8], *page; + unsigned long count, priv; + unsigned n, offset, to, f, t; + pgoff_t start, first, last; + int loop, ret; + + _enter(",%lx", primary_page->index); + + count = 1; + if (test_set_page_writeback(primary_page)) + BUG(); + + /* Find all consecutive lockable dirty pages that have contiguous + * written regions, stopping when we find a page that is not + * immediately lockable, is not dirty or is missing, or we reach the + * end of the range. + */ + start = primary_page->index; + priv = page_private(primary_page); + offset = priv & AFS_PRIV_MAX; + to = priv >> AFS_PRIV_SHIFT; + trace_afs_page_dirty(vnode, tracepoint_string("store"), + primary_page->index, priv); + + WARN_ON(offset == to); + if (offset == to) + trace_afs_page_dirty(vnode, tracepoint_string("WARN"), + primary_page->index, priv); + + if (start >= final_page || + (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))) + goto no_more; + + start++; + do { + _debug("more %lx [%lx]", start, count); + n = final_page - start + 1; + if (n > ARRAY_SIZE(pages)) + n = ARRAY_SIZE(pages); + n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages); + _debug("fgpc %u", n); + if (n == 0) + goto no_more; + if (pages[0]->index != start) { + do { + put_page(pages[--n]); + } while (n > 0); + goto no_more; + } + + for (loop = 0; loop < n; loop++) { + page = pages[loop]; + if (to != PAGE_SIZE && + !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) + break; + if (page->index > final_page) + break; + if (!trylock_page(page)) + break; + if (!PageDirty(page) || PageWriteback(page)) { + unlock_page(page); + break; + } + + priv = page_private(page); + f = priv & AFS_PRIV_MAX; + t = priv >> AFS_PRIV_SHIFT; + if (f != 0 && + !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) { + unlock_page(page); + break; + } + to = t; + + trace_afs_page_dirty(vnode, tracepoint_string("store+"), + page->index, priv); + + if (!clear_page_dirty_for_io(page)) + BUG(); + if (test_set_page_writeback(page)) + BUG(); + unlock_page(page); + put_page(page); + } + count += loop; + if (loop < n) { + for (; loop < n; loop++) + put_page(pages[loop]); + goto no_more; + } + + start += loop; + } while (start <= final_page && count < 65536); + +no_more: + /* We now have a contiguous set of dirty pages, each with writeback + * set; the first page is still locked at this point, but all the rest + * have been unlocked. + */ + unlock_page(primary_page); + + first = primary_page->index; + last = first + count - 1; + + _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to); + + ret = afs_store_data(mapping, first, last, offset, to); + switch (ret) { + case 0: + ret = count; + break; + + default: + pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret); + /* Fall through */ + case -EACCES: + case -EPERM: + case -ENOKEY: + case -EKEYEXPIRED: + case -EKEYREJECTED: + case -EKEYREVOKED: + afs_redirty_pages(wbc, mapping, first, last); + mapping_set_error(mapping, ret); + break; + + case -EDQUOT: + case -ENOSPC: + afs_redirty_pages(wbc, mapping, first, last); + mapping_set_error(mapping, -ENOSPC); + break; + + case -EROFS: + case -EIO: + case -EREMOTEIO: + case -EFBIG: + case -ENOENT: + case -ENOMEDIUM: + case -ENXIO: + afs_kill_pages(mapping, first, last); + mapping_set_error(mapping, ret); + break; + } + + _leave(" = %d", ret); + return ret; +} + +/* + * write a page back to the server + * - the caller locked the page for us + */ +int afs_writepage(struct page *page, struct writeback_control *wbc) +{ + int ret; + + _enter("{%lx},", page->index); + + ret = afs_write_back_from_locked_page(page->mapping, wbc, page, + wbc->range_end >> PAGE_SHIFT); + if (ret < 0) { + _leave(" = %d", ret); + return 0; + } + + wbc->nr_to_write -= ret; + + _leave(" = 0"); + return 0; +} + +/* + * write a region of pages back to the server + */ +static int afs_writepages_region(struct address_space *mapping, + struct writeback_control *wbc, + pgoff_t index, pgoff_t end, pgoff_t *_next) +{ + struct page *page; + int ret, n; + + _enter(",,%lx,%lx,", index, end); + + do { + n = find_get_pages_range_tag(mapping, &index, end, + PAGECACHE_TAG_DIRTY, 1, &page); + if (!n) + break; + + _debug("wback %lx", page->index); + + /* + * at this point we hold neither the i_pages lock nor the + * page lock: the page may be truncated or invalidated + * (changing page->mapping to NULL), or even swizzled + * back from swapper_space to tmpfs file mapping + */ + ret = lock_page_killable(page); + if (ret < 0) { + put_page(page); + _leave(" = %d", ret); + return ret; + } + + if (page->mapping != mapping || !PageDirty(page)) { + unlock_page(page); + put_page(page); + continue; + } + + if (PageWriteback(page)) { + unlock_page(page); + if (wbc->sync_mode != WB_SYNC_NONE) + wait_on_page_writeback(page); + put_page(page); + continue; + } + + if (!clear_page_dirty_for_io(page)) + BUG(); + ret = afs_write_back_from_locked_page(mapping, wbc, page, end); + put_page(page); + if (ret < 0) { + _leave(" = %d", ret); + return ret; + } + + wbc->nr_to_write -= ret; + + cond_resched(); + } while (index < end && wbc->nr_to_write > 0); + + *_next = index; + _leave(" = 0 [%lx]", *_next); + return 0; +} + +/* + * write some of the pending data back to the server + */ +int afs_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + pgoff_t start, end, next; + int ret; + + _enter(""); + + if (wbc->range_cyclic) { + start = mapping->writeback_index; + end = -1; + ret = afs_writepages_region(mapping, wbc, start, end, &next); + if (start > 0 && wbc->nr_to_write > 0 && ret == 0) + ret = afs_writepages_region(mapping, wbc, 0, start, + &next); + mapping->writeback_index = next; + } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) { + end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT); + ret = afs_writepages_region(mapping, wbc, 0, end, &next); + if (wbc->nr_to_write > 0) + mapping->writeback_index = next; + } else { + start = wbc->range_start >> PAGE_SHIFT; + end = wbc->range_end >> PAGE_SHIFT; + ret = afs_writepages_region(mapping, wbc, start, end, &next); + } + + _leave(" = %d", ret); + return ret; +} + +/* + * completion of write to server + */ +void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call) +{ + struct pagevec pv; + unsigned long priv; + unsigned count, loop; + pgoff_t first = call->first, last = call->last; + + _enter("{%x:%u},{%lx-%lx}", + vnode->fid.vid, vnode->fid.vnode, first, last); + + pagevec_init(&pv); + + do { + _debug("done %lx-%lx", first, last); + + count = last - first + 1; + if (count > PAGEVEC_SIZE) + count = PAGEVEC_SIZE; + pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping, + first, count, pv.pages); + ASSERTCMP(pv.nr, ==, count); + + for (loop = 0; loop < count; loop++) { + priv = page_private(pv.pages[loop]); + trace_afs_page_dirty(vnode, tracepoint_string("clear"), + pv.pages[loop]->index, priv); + set_page_private(pv.pages[loop], 0); + end_page_writeback(pv.pages[loop]); + } + first += count; + __pagevec_release(&pv); + } while (first <= last); + + afs_prune_wb_keys(vnode); + _leave(""); +} + +/* + * write to an AFS file + */ +ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from) +{ + struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp)); + ssize_t result; + size_t count = iov_iter_count(from); + + _enter("{%x.%u},{%zu},", + vnode->fid.vid, vnode->fid.vnode, count); + + if (IS_SWAPFILE(&vnode->vfs_inode)) { + printk(KERN_INFO + "AFS: Attempt to write to active swap file!\n"); + return -EBUSY; + } + + if (!count) + return 0; + + result = generic_file_write_iter(iocb, from); + + _leave(" = %zd", result); + return result; +} + +/* + * flush any dirty pages for this process, and check for write errors. + * - the return status from this call provides a reliable indication of + * whether any write errors occurred for this process. + */ +int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync) +{ + struct inode *inode = file_inode(file); + struct afs_vnode *vnode = AFS_FS_I(inode); + + _enter("{%x:%u},{n=%pD},%d", + vnode->fid.vid, vnode->fid.vnode, file, + datasync); + + return file_write_and_wait_range(file, start, end); +} + +/* + * notification that a previously read-only page is about to become writable + * - if it returns an error, the caller will deliver a bus error signal + */ +vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) +{ + struct file *file = vmf->vma->vm_file; + struct inode *inode = file_inode(file); + struct afs_vnode *vnode = AFS_FS_I(inode); + unsigned long priv; + + _enter("{{%x:%u}},{%lx}", + vnode->fid.vid, vnode->fid.vnode, vmf->page->index); + + sb_start_pagefault(inode->i_sb); + + /* Wait for the page to be written to the cache before we allow it to + * be modified. We then assume the entire page will need writing back. + */ +#ifdef CONFIG_AFS_FSCACHE + fscache_wait_on_page_write(vnode->cache, vmf->page); +#endif + + if (PageWriteback(vmf->page) && + wait_on_page_bit_killable(vmf->page, PG_writeback) < 0) + return VM_FAULT_RETRY; + + if (lock_page_killable(vmf->page) < 0) + return VM_FAULT_RETRY; + + /* We mustn't change page->private until writeback is complete as that + * details the portion of the page we need to write back and we might + * need to redirty the page if there's a problem. + */ + wait_on_page_writeback(vmf->page); + + priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */ + priv |= 0; /* From */ + trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), + vmf->page->index, priv); + SetPagePrivate(vmf->page); + set_page_private(vmf->page, priv); + file_update_time(file); + + sb_end_pagefault(inode->i_sb); + return VM_FAULT_LOCKED; +} + +/* + * Prune the keys cached for writeback. The caller must hold vnode->wb_lock. + */ +void afs_prune_wb_keys(struct afs_vnode *vnode) +{ + LIST_HEAD(graveyard); + struct afs_wb_key *wbk, *tmp; + + /* Discard unused keys */ + spin_lock(&vnode->wb_lock); + + if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) && + !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) { + list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) { + if (refcount_read(&wbk->usage) == 1) + list_move(&wbk->vnode_link, &graveyard); + } + } + + spin_unlock(&vnode->wb_lock); + + while (!list_empty(&graveyard)) { + wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link); + list_del(&wbk->vnode_link); + afs_put_wb_key(wbk); + } +} + +/* + * Clean up a page during invalidation. + */ +int afs_launder_page(struct page *page) +{ + struct address_space *mapping = page->mapping; + struct afs_vnode *vnode = AFS_FS_I(mapping->host); + unsigned long priv; + unsigned int f, t; + int ret = 0; + + _enter("{%lx}", page->index); + + priv = page_private(page); + if (clear_page_dirty_for_io(page)) { + f = 0; + t = PAGE_SIZE; + if (PagePrivate(page)) { + f = priv & AFS_PRIV_MAX; + t = priv >> AFS_PRIV_SHIFT; + } + + trace_afs_page_dirty(vnode, tracepoint_string("launder"), + page->index, priv); + ret = afs_store_data(mapping, page->index, page->index, t, f); + } + + trace_afs_page_dirty(vnode, tracepoint_string("laundered"), + page->index, priv); + set_page_private(page, 0); + ClearPagePrivate(page); + +#ifdef CONFIG_AFS_FSCACHE + if (PageFsCache(page)) { + fscache_wait_on_page_write(vnode->cache, page); + fscache_uncache_page(vnode->cache, page); + } +#endif + return ret; +} |