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-rw-r--r--fs/ubifs/file.c1678
1 files changed, 1678 insertions, 0 deletions
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
new file mode 100644
index 000000000..10c1779af
--- /dev/null
+++ b/fs/ubifs/file.c
@@ -0,0 +1,1678 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * Authors: Artem Bityutskiy (Битюцкий Артём)
+ * Adrian Hunter
+ */
+
+/*
+ * This file implements VFS file and inode operations for regular files, device
+ * nodes and symlinks as well as address space operations.
+ *
+ * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if
+ * the page is dirty and is used for optimization purposes - dirty pages are
+ * not budgeted so the flag shows that 'ubifs_write_end()' should not release
+ * the budget for this page. The @PG_checked flag is set if full budgeting is
+ * required for the page e.g., when it corresponds to a file hole or it is
+ * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because
+ * it is OK to fail in this function, and the budget is released in
+ * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry
+ * information about how the page was budgeted, to make it possible to release
+ * the budget properly.
+ *
+ * A thing to keep in mind: inode @i_mutex is locked in most VFS operations we
+ * implement. However, this is not true for 'ubifs_writepage()', which may be
+ * called with @i_mutex unlocked. For example, when flusher thread is doing
+ * background write-back, it calls 'ubifs_writepage()' with unlocked @i_mutex.
+ * At "normal" work-paths the @i_mutex is locked in 'ubifs_writepage()', e.g.
+ * in the "sys_write -> alloc_pages -> direct reclaim path". So, in
+ * 'ubifs_writepage()' we are only guaranteed that the page is locked.
+ *
+ * Similarly, @i_mutex is not always locked in 'ubifs_read_folio()', e.g., the
+ * read-ahead path does not lock it ("sys_read -> generic_file_aio_read ->
+ * ondemand_readahead -> read_folio"). In case of readahead, @I_SYNC flag is not
+ * set as well. However, UBIFS disables readahead.
+ */
+
+#include "ubifs.h"
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/migrate.h>
+
+static int read_block(struct inode *inode, void *addr, unsigned int block,
+ struct ubifs_data_node *dn)
+{
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ int err, len, out_len;
+ union ubifs_key key;
+ unsigned int dlen;
+
+ data_key_init(c, &key, inode->i_ino, block);
+ err = ubifs_tnc_lookup(c, &key, dn);
+ if (err) {
+ if (err == -ENOENT)
+ /* Not found, so it must be a hole */
+ memset(addr, 0, UBIFS_BLOCK_SIZE);
+ return err;
+ }
+
+ ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) >
+ ubifs_inode(inode)->creat_sqnum);
+ len = le32_to_cpu(dn->size);
+ if (len <= 0 || len > UBIFS_BLOCK_SIZE)
+ goto dump;
+
+ dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
+
+ if (IS_ENCRYPTED(inode)) {
+ err = ubifs_decrypt(inode, dn, &dlen, block);
+ if (err)
+ goto dump;
+ }
+
+ out_len = UBIFS_BLOCK_SIZE;
+ err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
+ le16_to_cpu(dn->compr_type));
+ if (err || len != out_len)
+ goto dump;
+
+ /*
+ * Data length can be less than a full block, even for blocks that are
+ * not the last in the file (e.g., as a result of making a hole and
+ * appending data). Ensure that the remainder is zeroed out.
+ */
+ if (len < UBIFS_BLOCK_SIZE)
+ memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
+
+ return 0;
+
+dump:
+ ubifs_err(c, "bad data node (block %u, inode %lu)",
+ block, inode->i_ino);
+ ubifs_dump_node(c, dn, UBIFS_MAX_DATA_NODE_SZ);
+ return -EINVAL;
+}
+
+static int do_readpage(struct page *page)
+{
+ void *addr;
+ int err = 0, i;
+ unsigned int block, beyond;
+ struct ubifs_data_node *dn;
+ struct inode *inode = page->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ loff_t i_size = i_size_read(inode);
+
+ dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
+ inode->i_ino, page->index, i_size, page->flags);
+ ubifs_assert(c, !PageChecked(page));
+ ubifs_assert(c, !PagePrivate(page));
+
+ addr = kmap(page);
+
+ block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
+ beyond = (i_size + UBIFS_BLOCK_SIZE - 1) >> UBIFS_BLOCK_SHIFT;
+ if (block >= beyond) {
+ /* Reading beyond inode */
+ SetPageChecked(page);
+ memset(addr, 0, PAGE_SIZE);
+ goto out;
+ }
+
+ dn = kmalloc(UBIFS_MAX_DATA_NODE_SZ, GFP_NOFS);
+ if (!dn) {
+ err = -ENOMEM;
+ goto error;
+ }
+
+ i = 0;
+ while (1) {
+ int ret;
+
+ if (block >= beyond) {
+ /* Reading beyond inode */
+ err = -ENOENT;
+ memset(addr, 0, UBIFS_BLOCK_SIZE);
+ } else {
+ ret = read_block(inode, addr, block, dn);
+ if (ret) {
+ err = ret;
+ if (err != -ENOENT)
+ break;
+ } else if (block + 1 == beyond) {
+ int dlen = le32_to_cpu(dn->size);
+ int ilen = i_size & (UBIFS_BLOCK_SIZE - 1);
+
+ if (ilen && ilen < dlen)
+ memset(addr + ilen, 0, dlen - ilen);
+ }
+ }
+ if (++i >= UBIFS_BLOCKS_PER_PAGE)
+ break;
+ block += 1;
+ addr += UBIFS_BLOCK_SIZE;
+ }
+ if (err) {
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ if (err == -ENOENT) {
+ /* Not found, so it must be a hole */
+ SetPageChecked(page);
+ dbg_gen("hole");
+ goto out_free;
+ }
+ ubifs_err(c, "cannot read page %lu of inode %lu, error %d",
+ page->index, inode->i_ino, err);
+ goto error;
+ }
+
+out_free:
+ kfree(dn);
+out:
+ SetPageUptodate(page);
+ ClearPageError(page);
+ flush_dcache_page(page);
+ kunmap(page);
+ return 0;
+
+error:
+ kfree(dn);
+ ClearPageUptodate(page);
+ SetPageError(page);
+ flush_dcache_page(page);
+ kunmap(page);
+ return err;
+}
+
+/**
+ * release_new_page_budget - release budget of a new page.
+ * @c: UBIFS file-system description object
+ *
+ * This is a helper function which releases budget corresponding to the budget
+ * of one new page of data.
+ */
+static void release_new_page_budget(struct ubifs_info *c)
+{
+ struct ubifs_budget_req req = { .recalculate = 1, .new_page = 1 };
+
+ ubifs_release_budget(c, &req);
+}
+
+/**
+ * release_existing_page_budget - release budget of an existing page.
+ * @c: UBIFS file-system description object
+ *
+ * This is a helper function which releases budget corresponding to the budget
+ * of changing one page of data which already exists on the flash media.
+ */
+static void release_existing_page_budget(struct ubifs_info *c)
+{
+ struct ubifs_budget_req req = { .dd_growth = c->bi.page_budget};
+
+ ubifs_release_budget(c, &req);
+}
+
+static int write_begin_slow(struct address_space *mapping,
+ loff_t pos, unsigned len, struct page **pagep)
+{
+ struct inode *inode = mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ pgoff_t index = pos >> PAGE_SHIFT;
+ struct ubifs_budget_req req = { .new_page = 1 };
+ int err, appending = !!(pos + len > inode->i_size);
+ struct page *page;
+
+ dbg_gen("ino %lu, pos %llu, len %u, i_size %lld",
+ inode->i_ino, pos, len, inode->i_size);
+
+ /*
+ * At the slow path we have to budget before locking the page, because
+ * budgeting may force write-back, which would wait on locked pages and
+ * deadlock if we had the page locked. At this point we do not know
+ * anything about the page, so assume that this is a new page which is
+ * written to a hole. This corresponds to largest budget. Later the
+ * budget will be amended if this is not true.
+ */
+ if (appending)
+ /* We are appending data, budget for inode change */
+ req.dirtied_ino = 1;
+
+ err = ubifs_budget_space(c, &req);
+ if (unlikely(err))
+ return err;
+
+ page = grab_cache_page_write_begin(mapping, index);
+ if (unlikely(!page)) {
+ ubifs_release_budget(c, &req);
+ return -ENOMEM;
+ }
+
+ if (!PageUptodate(page)) {
+ if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE)
+ SetPageChecked(page);
+ else {
+ err = do_readpage(page);
+ if (err) {
+ unlock_page(page);
+ put_page(page);
+ ubifs_release_budget(c, &req);
+ return err;
+ }
+ }
+
+ SetPageUptodate(page);
+ ClearPageError(page);
+ }
+
+ if (PagePrivate(page))
+ /*
+ * The page is dirty, which means it was budgeted twice:
+ * o first time the budget was allocated by the task which
+ * made the page dirty and set the PG_private flag;
+ * o and then we budgeted for it for the second time at the
+ * very beginning of this function.
+ *
+ * So what we have to do is to release the page budget we
+ * allocated.
+ */
+ release_new_page_budget(c);
+ else if (!PageChecked(page))
+ /*
+ * We are changing a page which already exists on the media.
+ * This means that changing the page does not make the amount
+ * of indexing information larger, and this part of the budget
+ * which we have already acquired may be released.
+ */
+ ubifs_convert_page_budget(c);
+
+ if (appending) {
+ struct ubifs_inode *ui = ubifs_inode(inode);
+
+ /*
+ * 'ubifs_write_end()' is optimized from the fast-path part of
+ * 'ubifs_write_begin()' and expects the @ui_mutex to be locked
+ * if data is appended.
+ */
+ mutex_lock(&ui->ui_mutex);
+ if (ui->dirty)
+ /*
+ * The inode is dirty already, so we may free the
+ * budget we allocated.
+ */
+ ubifs_release_dirty_inode_budget(c, ui);
+ }
+
+ *pagep = page;
+ return 0;
+}
+
+/**
+ * allocate_budget - allocate budget for 'ubifs_write_begin()'.
+ * @c: UBIFS file-system description object
+ * @page: page to allocate budget for
+ * @ui: UBIFS inode object the page belongs to
+ * @appending: non-zero if the page is appended
+ *
+ * This is a helper function for 'ubifs_write_begin()' which allocates budget
+ * for the operation. The budget is allocated differently depending on whether
+ * this is appending, whether the page is dirty or not, and so on. This
+ * function leaves the @ui->ui_mutex locked in case of appending. Returns zero
+ * in case of success and %-ENOSPC in case of failure.
+ */
+static int allocate_budget(struct ubifs_info *c, struct page *page,
+ struct ubifs_inode *ui, int appending)
+{
+ struct ubifs_budget_req req = { .fast = 1 };
+
+ if (PagePrivate(page)) {
+ if (!appending)
+ /*
+ * The page is dirty and we are not appending, which
+ * means no budget is needed at all.
+ */
+ return 0;
+
+ mutex_lock(&ui->ui_mutex);
+ if (ui->dirty)
+ /*
+ * The page is dirty and we are appending, so the inode
+ * has to be marked as dirty. However, it is already
+ * dirty, so we do not need any budget. We may return,
+ * but @ui->ui_mutex hast to be left locked because we
+ * should prevent write-back from flushing the inode
+ * and freeing the budget. The lock will be released in
+ * 'ubifs_write_end()'.
+ */
+ return 0;
+
+ /*
+ * The page is dirty, we are appending, the inode is clean, so
+ * we need to budget the inode change.
+ */
+ req.dirtied_ino = 1;
+ } else {
+ if (PageChecked(page))
+ /*
+ * The page corresponds to a hole and does not
+ * exist on the media. So changing it makes
+ * make the amount of indexing information
+ * larger, and we have to budget for a new
+ * page.
+ */
+ req.new_page = 1;
+ else
+ /*
+ * Not a hole, the change will not add any new
+ * indexing information, budget for page
+ * change.
+ */
+ req.dirtied_page = 1;
+
+ if (appending) {
+ mutex_lock(&ui->ui_mutex);
+ if (!ui->dirty)
+ /*
+ * The inode is clean but we will have to mark
+ * it as dirty because we are appending. This
+ * needs a budget.
+ */
+ req.dirtied_ino = 1;
+ }
+ }
+
+ return ubifs_budget_space(c, &req);
+}
+
+/*
+ * This function is called when a page of data is going to be written. Since
+ * the page of data will not necessarily go to the flash straight away, UBIFS
+ * has to reserve space on the media for it, which is done by means of
+ * budgeting.
+ *
+ * This is the hot-path of the file-system and we are trying to optimize it as
+ * much as possible. For this reasons it is split on 2 parts - slow and fast.
+ *
+ * There many budgeting cases:
+ * o a new page is appended - we have to budget for a new page and for
+ * changing the inode; however, if the inode is already dirty, there is
+ * no need to budget for it;
+ * o an existing clean page is changed - we have budget for it; if the page
+ * does not exist on the media (a hole), we have to budget for a new
+ * page; otherwise, we may budget for changing an existing page; the
+ * difference between these cases is that changing an existing page does
+ * not introduce anything new to the FS indexing information, so it does
+ * not grow, and smaller budget is acquired in this case;
+ * o an existing dirty page is changed - no need to budget at all, because
+ * the page budget has been acquired by earlier, when the page has been
+ * marked dirty.
+ *
+ * UBIFS budgeting sub-system may force write-back if it thinks there is no
+ * space to reserve. This imposes some locking restrictions and makes it
+ * impossible to take into account the above cases, and makes it impossible to
+ * optimize budgeting.
+ *
+ * The solution for this is that the fast path of 'ubifs_write_begin()' assumes
+ * there is a plenty of flash space and the budget will be acquired quickly,
+ * without forcing write-back. The slow path does not make this assumption.
+ */
+static int ubifs_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len,
+ struct page **pagep, void **fsdata)
+{
+ struct inode *inode = mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ pgoff_t index = pos >> PAGE_SHIFT;
+ int err, appending = !!(pos + len > inode->i_size);
+ int skipped_read = 0;
+ struct page *page;
+
+ ubifs_assert(c, ubifs_inode(inode)->ui_size == inode->i_size);
+ ubifs_assert(c, !c->ro_media && !c->ro_mount);
+
+ if (unlikely(c->ro_error))
+ return -EROFS;
+
+ /* Try out the fast-path part first */
+ page = grab_cache_page_write_begin(mapping, index);
+ if (unlikely(!page))
+ return -ENOMEM;
+
+ if (!PageUptodate(page)) {
+ /* The page is not loaded from the flash */
+ if (!(pos & ~PAGE_MASK) && len == PAGE_SIZE) {
+ /*
+ * We change whole page so no need to load it. But we
+ * do not know whether this page exists on the media or
+ * not, so we assume the latter because it requires
+ * larger budget. The assumption is that it is better
+ * to budget a bit more than to read the page from the
+ * media. Thus, we are setting the @PG_checked flag
+ * here.
+ */
+ SetPageChecked(page);
+ skipped_read = 1;
+ } else {
+ err = do_readpage(page);
+ if (err) {
+ unlock_page(page);
+ put_page(page);
+ return err;
+ }
+ }
+
+ SetPageUptodate(page);
+ ClearPageError(page);
+ }
+
+ err = allocate_budget(c, page, ui, appending);
+ if (unlikely(err)) {
+ ubifs_assert(c, err == -ENOSPC);
+ /*
+ * If we skipped reading the page because we were going to
+ * write all of it, then it is not up to date.
+ */
+ if (skipped_read) {
+ ClearPageChecked(page);
+ ClearPageUptodate(page);
+ }
+ /*
+ * Budgeting failed which means it would have to force
+ * write-back but didn't, because we set the @fast flag in the
+ * request. Write-back cannot be done now, while we have the
+ * page locked, because it would deadlock. Unlock and free
+ * everything and fall-back to slow-path.
+ */
+ if (appending) {
+ ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
+ mutex_unlock(&ui->ui_mutex);
+ }
+ unlock_page(page);
+ put_page(page);
+
+ return write_begin_slow(mapping, pos, len, pagep);
+ }
+
+ /*
+ * Whee, we acquired budgeting quickly - without involving
+ * garbage-collection, committing or forcing write-back. We return
+ * with @ui->ui_mutex locked if we are appending pages, and unlocked
+ * otherwise. This is an optimization (slightly hacky though).
+ */
+ *pagep = page;
+ return 0;
+
+}
+
+/**
+ * cancel_budget - cancel budget.
+ * @c: UBIFS file-system description object
+ * @page: page to cancel budget for
+ * @ui: UBIFS inode object the page belongs to
+ * @appending: non-zero if the page is appended
+ *
+ * This is a helper function for a page write operation. It unlocks the
+ * @ui->ui_mutex in case of appending.
+ */
+static void cancel_budget(struct ubifs_info *c, struct page *page,
+ struct ubifs_inode *ui, int appending)
+{
+ if (appending) {
+ if (!ui->dirty)
+ ubifs_release_dirty_inode_budget(c, ui);
+ mutex_unlock(&ui->ui_mutex);
+ }
+ if (!PagePrivate(page)) {
+ if (PageChecked(page))
+ release_new_page_budget(c);
+ else
+ release_existing_page_budget(c);
+ }
+}
+
+static int ubifs_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ struct inode *inode = mapping->host;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ loff_t end_pos = pos + len;
+ int appending = !!(end_pos > inode->i_size);
+
+ dbg_gen("ino %lu, pos %llu, pg %lu, len %u, copied %d, i_size %lld",
+ inode->i_ino, pos, page->index, len, copied, inode->i_size);
+
+ if (unlikely(copied < len && len == PAGE_SIZE)) {
+ /*
+ * VFS copied less data to the page that it intended and
+ * declared in its '->write_begin()' call via the @len
+ * argument. If the page was not up-to-date, and @len was
+ * @PAGE_SIZE, the 'ubifs_write_begin()' function did
+ * not load it from the media (for optimization reasons). This
+ * means that part of the page contains garbage. So read the
+ * page now.
+ */
+ dbg_gen("copied %d instead of %d, read page and repeat",
+ copied, len);
+ cancel_budget(c, page, ui, appending);
+ ClearPageChecked(page);
+
+ /*
+ * Return 0 to force VFS to repeat the whole operation, or the
+ * error code if 'do_readpage()' fails.
+ */
+ copied = do_readpage(page);
+ goto out;
+ }
+
+ if (!PagePrivate(page)) {
+ attach_page_private(page, (void *)1);
+ atomic_long_inc(&c->dirty_pg_cnt);
+ __set_page_dirty_nobuffers(page);
+ }
+
+ if (appending) {
+ i_size_write(inode, end_pos);
+ ui->ui_size = end_pos;
+ /*
+ * Note, we do not set @I_DIRTY_PAGES (which means that the
+ * inode has dirty pages), this has been done in
+ * '__set_page_dirty_nobuffers()'.
+ */
+ __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+ ubifs_assert(c, mutex_is_locked(&ui->ui_mutex));
+ mutex_unlock(&ui->ui_mutex);
+ }
+
+out:
+ unlock_page(page);
+ put_page(page);
+ return copied;
+}
+
+/**
+ * populate_page - copy data nodes into a page for bulk-read.
+ * @c: UBIFS file-system description object
+ * @page: page
+ * @bu: bulk-read information
+ * @n: next zbranch slot
+ *
+ * This function returns %0 on success and a negative error code on failure.
+ */
+static int populate_page(struct ubifs_info *c, struct page *page,
+ struct bu_info *bu, int *n)
+{
+ int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 0, read = 0;
+ struct inode *inode = page->mapping->host;
+ loff_t i_size = i_size_read(inode);
+ unsigned int page_block;
+ void *addr, *zaddr;
+ pgoff_t end_index;
+
+ dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx",
+ inode->i_ino, page->index, i_size, page->flags);
+
+ addr = zaddr = kmap(page);
+
+ end_index = (i_size - 1) >> PAGE_SHIFT;
+ if (!i_size || page->index > end_index) {
+ hole = 1;
+ memset(addr, 0, PAGE_SIZE);
+ goto out_hole;
+ }
+
+ page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
+ while (1) {
+ int err, len, out_len, dlen;
+
+ if (nn >= bu->cnt) {
+ hole = 1;
+ memset(addr, 0, UBIFS_BLOCK_SIZE);
+ } else if (key_block(c, &bu->zbranch[nn].key) == page_block) {
+ struct ubifs_data_node *dn;
+
+ dn = bu->buf + (bu->zbranch[nn].offs - offs);
+
+ ubifs_assert(c, le64_to_cpu(dn->ch.sqnum) >
+ ubifs_inode(inode)->creat_sqnum);
+
+ len = le32_to_cpu(dn->size);
+ if (len <= 0 || len > UBIFS_BLOCK_SIZE)
+ goto out_err;
+
+ dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
+ out_len = UBIFS_BLOCK_SIZE;
+
+ if (IS_ENCRYPTED(inode)) {
+ err = ubifs_decrypt(inode, dn, &dlen, page_block);
+ if (err)
+ goto out_err;
+ }
+
+ err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
+ le16_to_cpu(dn->compr_type));
+ if (err || len != out_len)
+ goto out_err;
+
+ if (len < UBIFS_BLOCK_SIZE)
+ memset(addr + len, 0, UBIFS_BLOCK_SIZE - len);
+
+ nn += 1;
+ read = (i << UBIFS_BLOCK_SHIFT) + len;
+ } else if (key_block(c, &bu->zbranch[nn].key) < page_block) {
+ nn += 1;
+ continue;
+ } else {
+ hole = 1;
+ memset(addr, 0, UBIFS_BLOCK_SIZE);
+ }
+ if (++i >= UBIFS_BLOCKS_PER_PAGE)
+ break;
+ addr += UBIFS_BLOCK_SIZE;
+ page_block += 1;
+ }
+
+ if (end_index == page->index) {
+ int len = i_size & (PAGE_SIZE - 1);
+
+ if (len && len < read)
+ memset(zaddr + len, 0, read - len);
+ }
+
+out_hole:
+ if (hole) {
+ SetPageChecked(page);
+ dbg_gen("hole");
+ }
+
+ SetPageUptodate(page);
+ ClearPageError(page);
+ flush_dcache_page(page);
+ kunmap(page);
+ *n = nn;
+ return 0;
+
+out_err:
+ ClearPageUptodate(page);
+ SetPageError(page);
+ flush_dcache_page(page);
+ kunmap(page);
+ ubifs_err(c, "bad data node (block %u, inode %lu)",
+ page_block, inode->i_ino);
+ return -EINVAL;
+}
+
+/**
+ * ubifs_do_bulk_read - do bulk-read.
+ * @c: UBIFS file-system description object
+ * @bu: bulk-read information
+ * @page1: first page to read
+ *
+ * This function returns %1 if the bulk-read is done, otherwise %0 is returned.
+ */
+static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu,
+ struct page *page1)
+{
+ pgoff_t offset = page1->index, end_index;
+ struct address_space *mapping = page1->mapping;
+ struct inode *inode = mapping->host;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ int err, page_idx, page_cnt, ret = 0, n = 0;
+ int allocate = bu->buf ? 0 : 1;
+ loff_t isize;
+ gfp_t ra_gfp_mask = readahead_gfp_mask(mapping) & ~__GFP_FS;
+
+ err = ubifs_tnc_get_bu_keys(c, bu);
+ if (err)
+ goto out_warn;
+
+ if (bu->eof) {
+ /* Turn off bulk-read at the end of the file */
+ ui->read_in_a_row = 1;
+ ui->bulk_read = 0;
+ }
+
+ page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT;
+ if (!page_cnt) {
+ /*
+ * This happens when there are multiple blocks per page and the
+ * blocks for the first page we are looking for, are not
+ * together. If all the pages were like this, bulk-read would
+ * reduce performance, so we turn it off for a while.
+ */
+ goto out_bu_off;
+ }
+
+ if (bu->cnt) {
+ if (allocate) {
+ /*
+ * Allocate bulk-read buffer depending on how many data
+ * nodes we are going to read.
+ */
+ bu->buf_len = bu->zbranch[bu->cnt - 1].offs +
+ bu->zbranch[bu->cnt - 1].len -
+ bu->zbranch[0].offs;
+ ubifs_assert(c, bu->buf_len > 0);
+ ubifs_assert(c, bu->buf_len <= c->leb_size);
+ bu->buf = kmalloc(bu->buf_len, GFP_NOFS | __GFP_NOWARN);
+ if (!bu->buf)
+ goto out_bu_off;
+ }
+
+ err = ubifs_tnc_bulk_read(c, bu);
+ if (err)
+ goto out_warn;
+ }
+
+ err = populate_page(c, page1, bu, &n);
+ if (err)
+ goto out_warn;
+
+ unlock_page(page1);
+ ret = 1;
+
+ isize = i_size_read(inode);
+ if (isize == 0)
+ goto out_free;
+ end_index = ((isize - 1) >> PAGE_SHIFT);
+
+ for (page_idx = 1; page_idx < page_cnt; page_idx++) {
+ pgoff_t page_offset = offset + page_idx;
+ struct page *page;
+
+ if (page_offset > end_index)
+ break;
+ page = pagecache_get_page(mapping, page_offset,
+ FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT,
+ ra_gfp_mask);
+ if (!page)
+ break;
+ if (!PageUptodate(page))
+ err = populate_page(c, page, bu, &n);
+ unlock_page(page);
+ put_page(page);
+ if (err)
+ break;
+ }
+
+ ui->last_page_read = offset + page_idx - 1;
+
+out_free:
+ if (allocate)
+ kfree(bu->buf);
+ return ret;
+
+out_warn:
+ ubifs_warn(c, "ignoring error %d and skipping bulk-read", err);
+ goto out_free;
+
+out_bu_off:
+ ui->read_in_a_row = ui->bulk_read = 0;
+ goto out_free;
+}
+
+/**
+ * ubifs_bulk_read - determine whether to bulk-read and, if so, do it.
+ * @page: page from which to start bulk-read.
+ *
+ * Some flash media are capable of reading sequentially at faster rates. UBIFS
+ * bulk-read facility is designed to take advantage of that, by reading in one
+ * go consecutive data nodes that are also located consecutively in the same
+ * LEB. This function returns %1 if a bulk-read is done and %0 otherwise.
+ */
+static int ubifs_bulk_read(struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ pgoff_t index = page->index, last_page_read = ui->last_page_read;
+ struct bu_info *bu;
+ int err = 0, allocated = 0;
+
+ ui->last_page_read = index;
+ if (!c->bulk_read)
+ return 0;
+
+ /*
+ * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
+ * so don't bother if we cannot lock the mutex.
+ */
+ if (!mutex_trylock(&ui->ui_mutex))
+ return 0;
+
+ if (index != last_page_read + 1) {
+ /* Turn off bulk-read if we stop reading sequentially */
+ ui->read_in_a_row = 1;
+ if (ui->bulk_read)
+ ui->bulk_read = 0;
+ goto out_unlock;
+ }
+
+ if (!ui->bulk_read) {
+ ui->read_in_a_row += 1;
+ if (ui->read_in_a_row < 3)
+ goto out_unlock;
+ /* Three reads in a row, so switch on bulk-read */
+ ui->bulk_read = 1;
+ }
+
+ /*
+ * If possible, try to use pre-allocated bulk-read information, which
+ * is protected by @c->bu_mutex.
+ */
+ if (mutex_trylock(&c->bu_mutex))
+ bu = &c->bu;
+ else {
+ bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
+ if (!bu)
+ goto out_unlock;
+
+ bu->buf = NULL;
+ allocated = 1;
+ }
+
+ bu->buf_len = c->max_bu_buf_len;
+ data_key_init(c, &bu->key, inode->i_ino,
+ page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
+ err = ubifs_do_bulk_read(c, bu, page);
+
+ if (!allocated)
+ mutex_unlock(&c->bu_mutex);
+ else
+ kfree(bu);
+
+out_unlock:
+ mutex_unlock(&ui->ui_mutex);
+ return err;
+}
+
+static int ubifs_read_folio(struct file *file, struct folio *folio)
+{
+ struct page *page = &folio->page;
+
+ if (ubifs_bulk_read(page))
+ return 0;
+ do_readpage(page);
+ folio_unlock(folio);
+ return 0;
+}
+
+static int do_writepage(struct page *page, int len)
+{
+ int err = 0, i, blen;
+ unsigned int block;
+ void *addr;
+ union ubifs_key key;
+ struct inode *inode = page->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+#ifdef UBIFS_DEBUG
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ spin_lock(&ui->ui_lock);
+ ubifs_assert(c, page->index <= ui->synced_i_size >> PAGE_SHIFT);
+ spin_unlock(&ui->ui_lock);
+#endif
+
+ /* Update radix tree tags */
+ set_page_writeback(page);
+
+ addr = kmap(page);
+ block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT;
+ i = 0;
+ while (len) {
+ blen = min_t(int, len, UBIFS_BLOCK_SIZE);
+ data_key_init(c, &key, inode->i_ino, block);
+ err = ubifs_jnl_write_data(c, inode, &key, addr, blen);
+ if (err)
+ break;
+ if (++i >= UBIFS_BLOCKS_PER_PAGE)
+ break;
+ block += 1;
+ addr += blen;
+ len -= blen;
+ }
+ if (err) {
+ SetPageError(page);
+ ubifs_err(c, "cannot write page %lu of inode %lu, error %d",
+ page->index, inode->i_ino, err);
+ ubifs_ro_mode(c, err);
+ }
+
+ ubifs_assert(c, PagePrivate(page));
+ if (PageChecked(page))
+ release_new_page_budget(c);
+ else
+ release_existing_page_budget(c);
+
+ atomic_long_dec(&c->dirty_pg_cnt);
+ detach_page_private(page);
+ ClearPageChecked(page);
+
+ kunmap(page);
+ unlock_page(page);
+ end_page_writeback(page);
+ return err;
+}
+
+/*
+ * When writing-back dirty inodes, VFS first writes-back pages belonging to the
+ * inode, then the inode itself. For UBIFS this may cause a problem. Consider a
+ * situation when a we have an inode with size 0, then a megabyte of data is
+ * appended to the inode, then write-back starts and flushes some amount of the
+ * dirty pages, the journal becomes full, commit happens and finishes, and then
+ * an unclean reboot happens. When the file system is mounted next time, the
+ * inode size would still be 0, but there would be many pages which are beyond
+ * the inode size, they would be indexed and consume flash space. Because the
+ * journal has been committed, the replay would not be able to detect this
+ * situation and correct the inode size. This means UBIFS would have to scan
+ * whole index and correct all inode sizes, which is long an unacceptable.
+ *
+ * To prevent situations like this, UBIFS writes pages back only if they are
+ * within the last synchronized inode size, i.e. the size which has been
+ * written to the flash media last time. Otherwise, UBIFS forces inode
+ * write-back, thus making sure the on-flash inode contains current inode size,
+ * and then keeps writing pages back.
+ *
+ * Some locking issues explanation. 'ubifs_writepage()' first is called with
+ * the page locked, and it locks @ui_mutex. However, write-back does take inode
+ * @i_mutex, which means other VFS operations may be run on this inode at the
+ * same time. And the problematic one is truncation to smaller size, from where
+ * we have to call 'truncate_setsize()', which first changes @inode->i_size,
+ * then drops the truncated pages. And while dropping the pages, it takes the
+ * page lock. This means that 'do_truncation()' cannot call 'truncate_setsize()'
+ * with @ui_mutex locked, because it would deadlock with 'ubifs_writepage()'.
+ * This means that @inode->i_size is changed while @ui_mutex is unlocked.
+ *
+ * XXX(truncate): with the new truncate sequence this is not true anymore,
+ * and the calls to truncate_setsize can be move around freely. They should
+ * be moved to the very end of the truncate sequence.
+ *
+ * But in 'ubifs_writepage()' we have to guarantee that we do not write beyond
+ * inode size. How do we do this if @inode->i_size may became smaller while we
+ * are in the middle of 'ubifs_writepage()'? The UBIFS solution is the
+ * @ui->ui_isize "shadow" field which UBIFS uses instead of @inode->i_size
+ * internally and updates it under @ui_mutex.
+ *
+ * Q: why we do not worry that if we race with truncation, we may end up with a
+ * situation when the inode is truncated while we are in the middle of
+ * 'do_writepage()', so we do write beyond inode size?
+ * A: If we are in the middle of 'do_writepage()', truncation would be locked
+ * on the page lock and it would not write the truncated inode node to the
+ * journal before we have finished.
+ */
+static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ loff_t i_size = i_size_read(inode), synced_i_size;
+ pgoff_t end_index = i_size >> PAGE_SHIFT;
+ int err, len = i_size & (PAGE_SIZE - 1);
+ void *kaddr;
+
+ dbg_gen("ino %lu, pg %lu, pg flags %#lx",
+ inode->i_ino, page->index, page->flags);
+ ubifs_assert(c, PagePrivate(page));
+
+ /* Is the page fully outside @i_size? (truncate in progress) */
+ if (page->index > end_index || (page->index == end_index && !len)) {
+ err = 0;
+ goto out_unlock;
+ }
+
+ spin_lock(&ui->ui_lock);
+ synced_i_size = ui->synced_i_size;
+ spin_unlock(&ui->ui_lock);
+
+ /* Is the page fully inside @i_size? */
+ if (page->index < end_index) {
+ if (page->index >= synced_i_size >> PAGE_SHIFT) {
+ err = inode->i_sb->s_op->write_inode(inode, NULL);
+ if (err)
+ goto out_redirty;
+ /*
+ * The inode has been written, but the write-buffer has
+ * not been synchronized, so in case of an unclean
+ * reboot we may end up with some pages beyond inode
+ * size, but they would be in the journal (because
+ * commit flushes write buffers) and recovery would deal
+ * with this.
+ */
+ }
+ return do_writepage(page, PAGE_SIZE);
+ }
+
+ /*
+ * The page straddles @i_size. It must be zeroed out on each and every
+ * writepage invocation because it may be mmapped. "A file is mapped
+ * in multiples of the page size. For a file that is not a multiple of
+ * the page size, the remaining memory is zeroed when mapped, and
+ * writes to that region are not written out to the file."
+ */
+ kaddr = kmap_atomic(page);
+ memset(kaddr + len, 0, PAGE_SIZE - len);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr);
+
+ if (i_size > synced_i_size) {
+ err = inode->i_sb->s_op->write_inode(inode, NULL);
+ if (err)
+ goto out_redirty;
+ }
+
+ return do_writepage(page, len);
+out_redirty:
+ /*
+ * redirty_page_for_writepage() won't call ubifs_dirty_inode() because
+ * it passes I_DIRTY_PAGES flag while calling __mark_inode_dirty(), so
+ * there is no need to do space budget for dirty inode.
+ */
+ redirty_page_for_writepage(wbc, page);
+out_unlock:
+ unlock_page(page);
+ return err;
+}
+
+/**
+ * do_attr_changes - change inode attributes.
+ * @inode: inode to change attributes for
+ * @attr: describes attributes to change
+ */
+static void do_attr_changes(struct inode *inode, const struct iattr *attr)
+{
+ if (attr->ia_valid & ATTR_UID)
+ inode->i_uid = attr->ia_uid;
+ if (attr->ia_valid & ATTR_GID)
+ inode->i_gid = attr->ia_gid;
+ if (attr->ia_valid & ATTR_ATIME)
+ inode->i_atime = attr->ia_atime;
+ if (attr->ia_valid & ATTR_MTIME)
+ inode->i_mtime = attr->ia_mtime;
+ if (attr->ia_valid & ATTR_CTIME)
+ inode->i_ctime = attr->ia_ctime;
+ if (attr->ia_valid & ATTR_MODE) {
+ umode_t mode = attr->ia_mode;
+
+ if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+ mode &= ~S_ISGID;
+ inode->i_mode = mode;
+ }
+}
+
+/**
+ * do_truncation - truncate an inode.
+ * @c: UBIFS file-system description object
+ * @inode: inode to truncate
+ * @attr: inode attribute changes description
+ *
+ * This function implements VFS '->setattr()' call when the inode is truncated
+ * to a smaller size. Returns zero in case of success and a negative error code
+ * in case of failure.
+ */
+static int do_truncation(struct ubifs_info *c, struct inode *inode,
+ const struct iattr *attr)
+{
+ int err;
+ struct ubifs_budget_req req;
+ loff_t old_size = inode->i_size, new_size = attr->ia_size;
+ int offset = new_size & (UBIFS_BLOCK_SIZE - 1), budgeted = 1;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+
+ dbg_gen("ino %lu, size %lld -> %lld", inode->i_ino, old_size, new_size);
+ memset(&req, 0, sizeof(struct ubifs_budget_req));
+
+ /*
+ * If this is truncation to a smaller size, and we do not truncate on a
+ * block boundary, budget for changing one data block, because the last
+ * block will be re-written.
+ */
+ if (new_size & (UBIFS_BLOCK_SIZE - 1))
+ req.dirtied_page = 1;
+
+ req.dirtied_ino = 1;
+ /* A funny way to budget for truncation node */
+ req.dirtied_ino_d = UBIFS_TRUN_NODE_SZ;
+ err = ubifs_budget_space(c, &req);
+ if (err) {
+ /*
+ * Treat truncations to zero as deletion and always allow them,
+ * just like we do for '->unlink()'.
+ */
+ if (new_size || err != -ENOSPC)
+ return err;
+ budgeted = 0;
+ }
+
+ truncate_setsize(inode, new_size);
+
+ if (offset) {
+ pgoff_t index = new_size >> PAGE_SHIFT;
+ struct page *page;
+
+ page = find_lock_page(inode->i_mapping, index);
+ if (page) {
+ if (PageDirty(page)) {
+ /*
+ * 'ubifs_jnl_truncate()' will try to truncate
+ * the last data node, but it contains
+ * out-of-date data because the page is dirty.
+ * Write the page now, so that
+ * 'ubifs_jnl_truncate()' will see an already
+ * truncated (and up to date) data node.
+ */
+ ubifs_assert(c, PagePrivate(page));
+
+ clear_page_dirty_for_io(page);
+ if (UBIFS_BLOCKS_PER_PAGE_SHIFT)
+ offset = new_size &
+ (PAGE_SIZE - 1);
+ err = do_writepage(page, offset);
+ put_page(page);
+ if (err)
+ goto out_budg;
+ /*
+ * We could now tell 'ubifs_jnl_truncate()' not
+ * to read the last block.
+ */
+ } else {
+ /*
+ * We could 'kmap()' the page and pass the data
+ * to 'ubifs_jnl_truncate()' to save it from
+ * having to read it.
+ */
+ unlock_page(page);
+ put_page(page);
+ }
+ }
+ }
+
+ mutex_lock(&ui->ui_mutex);
+ ui->ui_size = inode->i_size;
+ /* Truncation changes inode [mc]time */
+ inode->i_mtime = inode->i_ctime = current_time(inode);
+ /* Other attributes may be changed at the same time as well */
+ do_attr_changes(inode, attr);
+ err = ubifs_jnl_truncate(c, inode, old_size, new_size);
+ mutex_unlock(&ui->ui_mutex);
+
+out_budg:
+ if (budgeted)
+ ubifs_release_budget(c, &req);
+ else {
+ c->bi.nospace = c->bi.nospace_rp = 0;
+ smp_wmb();
+ }
+ return err;
+}
+
+/**
+ * do_setattr - change inode attributes.
+ * @c: UBIFS file-system description object
+ * @inode: inode to change attributes for
+ * @attr: inode attribute changes description
+ *
+ * This function implements VFS '->setattr()' call for all cases except
+ * truncations to smaller size. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+static int do_setattr(struct ubifs_info *c, struct inode *inode,
+ const struct iattr *attr)
+{
+ int err, release;
+ loff_t new_size = attr->ia_size;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ struct ubifs_budget_req req = { .dirtied_ino = 1,
+ .dirtied_ino_d = ALIGN(ui->data_len, 8) };
+
+ err = ubifs_budget_space(c, &req);
+ if (err)
+ return err;
+
+ if (attr->ia_valid & ATTR_SIZE) {
+ dbg_gen("size %lld -> %lld", inode->i_size, new_size);
+ truncate_setsize(inode, new_size);
+ }
+
+ mutex_lock(&ui->ui_mutex);
+ if (attr->ia_valid & ATTR_SIZE) {
+ /* Truncation changes inode [mc]time */
+ inode->i_mtime = inode->i_ctime = current_time(inode);
+ /* 'truncate_setsize()' changed @i_size, update @ui_size */
+ ui->ui_size = inode->i_size;
+ }
+
+ do_attr_changes(inode, attr);
+
+ release = ui->dirty;
+ if (attr->ia_valid & ATTR_SIZE)
+ /*
+ * Inode length changed, so we have to make sure
+ * @I_DIRTY_DATASYNC is set.
+ */
+ __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+ else
+ mark_inode_dirty_sync(inode);
+ mutex_unlock(&ui->ui_mutex);
+
+ if (release)
+ ubifs_release_budget(c, &req);
+ if (IS_SYNC(inode))
+ err = inode->i_sb->s_op->write_inode(inode, NULL);
+ return err;
+}
+
+int ubifs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct iattr *attr)
+{
+ int err;
+ struct inode *inode = d_inode(dentry);
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+ dbg_gen("ino %lu, mode %#x, ia_valid %#x",
+ inode->i_ino, inode->i_mode, attr->ia_valid);
+ err = setattr_prepare(&init_user_ns, dentry, attr);
+ if (err)
+ return err;
+
+ err = dbg_check_synced_i_size(c, inode);
+ if (err)
+ return err;
+
+ err = fscrypt_prepare_setattr(dentry, attr);
+ if (err)
+ return err;
+
+ if ((attr->ia_valid & ATTR_SIZE) && attr->ia_size < inode->i_size)
+ /* Truncation to a smaller size */
+ err = do_truncation(c, inode, attr);
+ else
+ err = do_setattr(c, inode, attr);
+
+ return err;
+}
+
+static void ubifs_invalidate_folio(struct folio *folio, size_t offset,
+ size_t length)
+{
+ struct inode *inode = folio->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+ ubifs_assert(c, folio_test_private(folio));
+ if (offset || length < folio_size(folio))
+ /* Partial folio remains dirty */
+ return;
+
+ if (folio_test_checked(folio))
+ release_new_page_budget(c);
+ else
+ release_existing_page_budget(c);
+
+ atomic_long_dec(&c->dirty_pg_cnt);
+ folio_detach_private(folio);
+ folio_clear_checked(folio);
+}
+
+int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+ struct inode *inode = file->f_mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ int err;
+
+ dbg_gen("syncing inode %lu", inode->i_ino);
+
+ if (c->ro_mount)
+ /*
+ * For some really strange reasons VFS does not filter out
+ * 'fsync()' for R/O mounted file-systems as per 2.6.39.
+ */
+ return 0;
+
+ err = file_write_and_wait_range(file, start, end);
+ if (err)
+ return err;
+ inode_lock(inode);
+
+ /* Synchronize the inode unless this is a 'datasync()' call. */
+ if (!datasync || (inode->i_state & I_DIRTY_DATASYNC)) {
+ err = inode->i_sb->s_op->write_inode(inode, NULL);
+ if (err)
+ goto out;
+ }
+
+ /*
+ * Nodes related to this inode may still sit in a write-buffer. Flush
+ * them.
+ */
+ err = ubifs_sync_wbufs_by_inode(c, inode);
+out:
+ inode_unlock(inode);
+ return err;
+}
+
+/**
+ * mctime_update_needed - check if mtime or ctime update is needed.
+ * @inode: the inode to do the check for
+ * @now: current time
+ *
+ * This helper function checks if the inode mtime/ctime should be updated or
+ * not. If current values of the time-stamps are within the UBIFS inode time
+ * granularity, they are not updated. This is an optimization.
+ */
+static inline int mctime_update_needed(const struct inode *inode,
+ const struct timespec64 *now)
+{
+ if (!timespec64_equal(&inode->i_mtime, now) ||
+ !timespec64_equal(&inode->i_ctime, now))
+ return 1;
+ return 0;
+}
+
+/**
+ * ubifs_update_time - update time of inode.
+ * @inode: inode to update
+ *
+ * This function updates time of the inode.
+ */
+int ubifs_update_time(struct inode *inode, struct timespec64 *time,
+ int flags)
+{
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ struct ubifs_budget_req req = { .dirtied_ino = 1,
+ .dirtied_ino_d = ALIGN(ui->data_len, 8) };
+ int err, release;
+
+ if (!IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
+ return generic_update_time(inode, time, flags);
+
+ err = ubifs_budget_space(c, &req);
+ if (err)
+ return err;
+
+ mutex_lock(&ui->ui_mutex);
+ if (flags & S_ATIME)
+ inode->i_atime = *time;
+ if (flags & S_CTIME)
+ inode->i_ctime = *time;
+ if (flags & S_MTIME)
+ inode->i_mtime = *time;
+
+ release = ui->dirty;
+ __mark_inode_dirty(inode, I_DIRTY_SYNC);
+ mutex_unlock(&ui->ui_mutex);
+ if (release)
+ ubifs_release_budget(c, &req);
+ return 0;
+}
+
+/**
+ * update_mctime - update mtime and ctime of an inode.
+ * @inode: inode to update
+ *
+ * This function updates mtime and ctime of the inode if it is not equivalent to
+ * current time. Returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int update_mctime(struct inode *inode)
+{
+ struct timespec64 now = current_time(inode);
+ struct ubifs_inode *ui = ubifs_inode(inode);
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+ if (mctime_update_needed(inode, &now)) {
+ int err, release;
+ struct ubifs_budget_req req = { .dirtied_ino = 1,
+ .dirtied_ino_d = ALIGN(ui->data_len, 8) };
+
+ err = ubifs_budget_space(c, &req);
+ if (err)
+ return err;
+
+ mutex_lock(&ui->ui_mutex);
+ inode->i_mtime = inode->i_ctime = current_time(inode);
+ release = ui->dirty;
+ mark_inode_dirty_sync(inode);
+ mutex_unlock(&ui->ui_mutex);
+ if (release)
+ ubifs_release_budget(c, &req);
+ }
+
+ return 0;
+}
+
+static ssize_t ubifs_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ int err = update_mctime(file_inode(iocb->ki_filp));
+ if (err)
+ return err;
+
+ return generic_file_write_iter(iocb, from);
+}
+
+static bool ubifs_dirty_folio(struct address_space *mapping,
+ struct folio *folio)
+{
+ bool ret;
+ struct ubifs_info *c = mapping->host->i_sb->s_fs_info;
+
+ ret = filemap_dirty_folio(mapping, folio);
+ /*
+ * An attempt to dirty a page without budgeting for it - should not
+ * happen.
+ */
+ ubifs_assert(c, ret == false);
+ return ret;
+}
+
+static bool ubifs_release_folio(struct folio *folio, gfp_t unused_gfp_flags)
+{
+ struct inode *inode = folio->mapping->host;
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+
+ if (folio_test_writeback(folio))
+ return false;
+
+ /*
+ * Page is private but not dirty, weird? There is one condition
+ * making it happened. ubifs_writepage skipped the page because
+ * page index beyonds isize (for example. truncated by other
+ * process named A), then the page is invalidated by fadvise64
+ * syscall before being truncated by process A.
+ */
+ ubifs_assert(c, folio_test_private(folio));
+ if (folio_test_checked(folio))
+ release_new_page_budget(c);
+ else
+ release_existing_page_budget(c);
+
+ atomic_long_dec(&c->dirty_pg_cnt);
+ folio_detach_private(folio);
+ folio_clear_checked(folio);
+ return true;
+}
+
+/*
+ * mmap()d file has taken write protection fault and is being made writable.
+ * UBIFS must ensure page is budgeted for.
+ */
+static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
+{
+ struct page *page = vmf->page;
+ struct inode *inode = file_inode(vmf->vma->vm_file);
+ struct ubifs_info *c = inode->i_sb->s_fs_info;
+ struct timespec64 now = current_time(inode);
+ struct ubifs_budget_req req = { .new_page = 1 };
+ int err, update_time;
+
+ dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index,
+ i_size_read(inode));
+ ubifs_assert(c, !c->ro_media && !c->ro_mount);
+
+ if (unlikely(c->ro_error))
+ return VM_FAULT_SIGBUS; /* -EROFS */
+
+ /*
+ * We have not locked @page so far so we may budget for changing the
+ * page. Note, we cannot do this after we locked the page, because
+ * budgeting may cause write-back which would cause deadlock.
+ *
+ * At the moment we do not know whether the page is dirty or not, so we
+ * assume that it is not and budget for a new page. We could look at
+ * the @PG_private flag and figure this out, but we may race with write
+ * back and the page state may change by the time we lock it, so this
+ * would need additional care. We do not bother with this at the
+ * moment, although it might be good idea to do. Instead, we allocate
+ * budget for a new page and amend it later on if the page was in fact
+ * dirty.
+ *
+ * The budgeting-related logic of this function is similar to what we
+ * do in 'ubifs_write_begin()' and 'ubifs_write_end()'. Glance there
+ * for more comments.
+ */
+ update_time = mctime_update_needed(inode, &now);
+ if (update_time)
+ /*
+ * We have to change inode time stamp which requires extra
+ * budgeting.
+ */
+ req.dirtied_ino = 1;
+
+ err = ubifs_budget_space(c, &req);
+ if (unlikely(err)) {
+ if (err == -ENOSPC)
+ ubifs_warn(c, "out of space for mmapped file (inode number %lu)",
+ inode->i_ino);
+ return VM_FAULT_SIGBUS;
+ }
+
+ lock_page(page);
+ if (unlikely(page->mapping != inode->i_mapping ||
+ page_offset(page) > i_size_read(inode))) {
+ /* Page got truncated out from underneath us */
+ goto sigbus;
+ }
+
+ if (PagePrivate(page))
+ release_new_page_budget(c);
+ else {
+ if (!PageChecked(page))
+ ubifs_convert_page_budget(c);
+ attach_page_private(page, (void *)1);
+ atomic_long_inc(&c->dirty_pg_cnt);
+ __set_page_dirty_nobuffers(page);
+ }
+
+ if (update_time) {
+ int release;
+ struct ubifs_inode *ui = ubifs_inode(inode);
+
+ mutex_lock(&ui->ui_mutex);
+ inode->i_mtime = inode->i_ctime = current_time(inode);
+ release = ui->dirty;
+ mark_inode_dirty_sync(inode);
+ mutex_unlock(&ui->ui_mutex);
+ if (release)
+ ubifs_release_dirty_inode_budget(c, ui);
+ }
+
+ wait_for_stable_page(page);
+ return VM_FAULT_LOCKED;
+
+sigbus:
+ unlock_page(page);
+ ubifs_release_budget(c, &req);
+ return VM_FAULT_SIGBUS;
+}
+
+static const struct vm_operations_struct ubifs_file_vm_ops = {
+ .fault = filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = ubifs_vm_page_mkwrite,
+};
+
+static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int err;
+
+ err = generic_file_mmap(file, vma);
+ if (err)
+ return err;
+ vma->vm_ops = &ubifs_file_vm_ops;
+
+ if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
+ file_accessed(file);
+
+ return 0;
+}
+
+static const char *ubifs_get_link(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ struct ubifs_inode *ui = ubifs_inode(inode);
+
+ if (!IS_ENCRYPTED(inode))
+ return ui->data;
+
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
+ return fscrypt_get_symlink(inode, ui->data, ui->data_len, done);
+}
+
+static int ubifs_symlink_getattr(struct user_namespace *mnt_userns,
+ const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
+{
+ ubifs_getattr(mnt_userns, path, stat, request_mask, query_flags);
+
+ if (IS_ENCRYPTED(d_inode(path->dentry)))
+ return fscrypt_symlink_getattr(path, stat);
+ return 0;
+}
+
+const struct address_space_operations ubifs_file_address_operations = {
+ .read_folio = ubifs_read_folio,
+ .writepage = ubifs_writepage,
+ .write_begin = ubifs_write_begin,
+ .write_end = ubifs_write_end,
+ .invalidate_folio = ubifs_invalidate_folio,
+ .dirty_folio = ubifs_dirty_folio,
+ .migrate_folio = filemap_migrate_folio,
+ .release_folio = ubifs_release_folio,
+};
+
+const struct inode_operations ubifs_file_inode_operations = {
+ .setattr = ubifs_setattr,
+ .getattr = ubifs_getattr,
+ .listxattr = ubifs_listxattr,
+ .update_time = ubifs_update_time,
+ .fileattr_get = ubifs_fileattr_get,
+ .fileattr_set = ubifs_fileattr_set,
+};
+
+const struct inode_operations ubifs_symlink_inode_operations = {
+ .get_link = ubifs_get_link,
+ .setattr = ubifs_setattr,
+ .getattr = ubifs_symlink_getattr,
+ .listxattr = ubifs_listxattr,
+ .update_time = ubifs_update_time,
+};
+
+const struct file_operations ubifs_file_operations = {
+ .llseek = generic_file_llseek,
+ .read_iter = generic_file_read_iter,
+ .write_iter = ubifs_write_iter,
+ .mmap = ubifs_file_mmap,
+ .fsync = ubifs_fsync,
+ .unlocked_ioctl = ubifs_ioctl,
+ .splice_read = generic_file_splice_read,
+ .splice_write = iter_file_splice_write,
+ .open = fscrypt_file_open,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = ubifs_compat_ioctl,
+#endif
+};