OSCL-LXR linux-6.0.1/​fs/​ubifs/​file.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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_unlock;
             /*
              * 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_unlock;
     }
 
     return do_writepage(page, len);
 
 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;
 
     /*
      * An attempt to release a dirty page without budgeting for it - should
      * not happen.
      */
     if (folio_test_writeback(folio))
         return false;
     ubifs_assert(c, folio_test_private(folio));
     ubifs_assert(c, 0);
     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
 };

This page was automatically generated by the 2.1.0 LXR engine. The LXR team