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cac2f8b8d8
The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. The current inode operation for getting posix acls takes an inode argument but various filesystems (e.g., 9p, cifs, overlayfs) need access to the dentry. In contrast to the ->set_acl() inode operation we cannot simply extend ->get_acl() to take a dentry argument. The ->get_acl() inode operation is called from: acl_permission_check() -> check_acl() -> get_acl() which is part of generic_permission() which in turn is part of inode_permission(). Both generic_permission() and inode_permission() are called in the ->permission() handler of various filesystems (e.g., overlayfs). So simply passing a dentry argument to ->get_acl() would amount to also having to pass a dentry argument to ->permission(). We should avoid this unnecessary change. So instead of extending the existing inode operation rename it from ->get_acl() to ->get_inode_acl() and add a ->get_acl() method later that passes a dentry argument and which filesystems that need access to the dentry can implement instead of ->get_inode_acl(). Filesystems like cifs which allow setting and getting posix acls but not using them for permission checking during lookup can simply not implement ->get_inode_acl(). This is intended to be a non-functional change. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Suggested-by/Inspired-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
264 lines
7.4 KiB
C
264 lines
7.4 KiB
C
/*
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* Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
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*/
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#include <linux/time.h>
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#include "reiserfs.h"
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#include "acl.h"
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#include "xattr.h"
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#include <linux/uaccess.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/quotaops.h>
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/*
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* We pack the tails of files on file close, not at the time they are written.
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* This implies an unnecessary copy of the tail and an unnecessary indirect item
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* insertion/balancing, for files that are written in one write.
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* It avoids unnecessary tail packings (balances) for files that are written in
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* multiple writes and are small enough to have tails.
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*
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* file_release is called by the VFS layer when the file is closed. If
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* this is the last open file descriptor, and the file
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* small enough to have a tail, and the tail is currently in an
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* unformatted node, the tail is converted back into a direct item.
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*
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* We use reiserfs_truncate_file to pack the tail, since it already has
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* all the conditions coded.
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*/
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static int reiserfs_file_release(struct inode *inode, struct file *filp)
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{
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struct reiserfs_transaction_handle th;
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int err;
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int jbegin_failure = 0;
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BUG_ON(!S_ISREG(inode->i_mode));
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if (!atomic_dec_and_mutex_lock(&REISERFS_I(inode)->openers,
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&REISERFS_I(inode)->tailpack))
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return 0;
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/* fast out for when nothing needs to be done */
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if ((!(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) ||
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!tail_has_to_be_packed(inode)) &&
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REISERFS_I(inode)->i_prealloc_count <= 0) {
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mutex_unlock(&REISERFS_I(inode)->tailpack);
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return 0;
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}
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reiserfs_write_lock(inode->i_sb);
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/*
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* freeing preallocation only involves relogging blocks that
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* are already in the current transaction. preallocation gets
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* freed at the end of each transaction, so it is impossible for
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* us to log any additional blocks (including quota blocks)
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*/
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err = journal_begin(&th, inode->i_sb, 1);
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if (err) {
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/*
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* uh oh, we can't allow the inode to go away while there
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* is still preallocation blocks pending. Try to join the
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* aborted transaction
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*/
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jbegin_failure = err;
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err = journal_join_abort(&th, inode->i_sb);
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if (err) {
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/*
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* hmpf, our choices here aren't good. We can pin
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* the inode which will disallow unmount from ever
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* happening, we can do nothing, which will corrupt
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* random memory on unmount, or we can forcibly
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* remove the file from the preallocation list, which
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* will leak blocks on disk. Lets pin the inode
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* and let the admin know what is going on.
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*/
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igrab(inode);
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reiserfs_warning(inode->i_sb, "clm-9001",
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"pinning inode %lu because the "
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"preallocation can't be freed",
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inode->i_ino);
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goto out;
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}
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}
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reiserfs_update_inode_transaction(inode);
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#ifdef REISERFS_PREALLOCATE
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reiserfs_discard_prealloc(&th, inode);
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#endif
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err = journal_end(&th);
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/* copy back the error code from journal_begin */
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if (!err)
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err = jbegin_failure;
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if (!err &&
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(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) &&
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tail_has_to_be_packed(inode)) {
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/*
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* if regular file is released by last holder and it has been
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* appended (we append by unformatted node only) or its direct
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* item(s) had to be converted, then it may have to be
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* indirect2direct converted
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*/
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err = reiserfs_truncate_file(inode, 0);
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}
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out:
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reiserfs_write_unlock(inode->i_sb);
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mutex_unlock(&REISERFS_I(inode)->tailpack);
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return err;
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}
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static int reiserfs_file_open(struct inode *inode, struct file *file)
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{
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int err = dquot_file_open(inode, file);
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/* somebody might be tailpacking on final close; wait for it */
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if (!atomic_inc_not_zero(&REISERFS_I(inode)->openers)) {
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mutex_lock(&REISERFS_I(inode)->tailpack);
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atomic_inc(&REISERFS_I(inode)->openers);
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mutex_unlock(&REISERFS_I(inode)->tailpack);
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}
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return err;
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}
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void reiserfs_vfs_truncate_file(struct inode *inode)
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{
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mutex_lock(&REISERFS_I(inode)->tailpack);
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reiserfs_truncate_file(inode, 1);
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mutex_unlock(&REISERFS_I(inode)->tailpack);
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}
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/* Sync a reiserfs file. */
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/*
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* FIXME: sync_mapping_buffers() never has anything to sync. Can
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* be removed...
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*/
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static int reiserfs_sync_file(struct file *filp, loff_t start, loff_t end,
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int datasync)
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{
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struct inode *inode = filp->f_mapping->host;
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int err;
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int barrier_done;
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err = file_write_and_wait_range(filp, start, end);
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if (err)
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return err;
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inode_lock(inode);
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BUG_ON(!S_ISREG(inode->i_mode));
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err = sync_mapping_buffers(inode->i_mapping);
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reiserfs_write_lock(inode->i_sb);
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barrier_done = reiserfs_commit_for_inode(inode);
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reiserfs_write_unlock(inode->i_sb);
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if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
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blkdev_issue_flush(inode->i_sb->s_bdev);
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inode_unlock(inode);
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if (barrier_done < 0)
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return barrier_done;
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return (err < 0) ? -EIO : 0;
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}
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/* taken fs/buffer.c:__block_commit_write */
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int reiserfs_commit_page(struct inode *inode, struct page *page,
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unsigned from, unsigned to)
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{
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unsigned block_start, block_end;
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int partial = 0;
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unsigned blocksize;
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struct buffer_head *bh, *head;
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unsigned long i_size_index = inode->i_size >> PAGE_SHIFT;
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int new;
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int logit = reiserfs_file_data_log(inode);
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struct super_block *s = inode->i_sb;
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int bh_per_page = PAGE_SIZE / s->s_blocksize;
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struct reiserfs_transaction_handle th;
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int ret = 0;
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th.t_trans_id = 0;
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blocksize = i_blocksize(inode);
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if (logit) {
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reiserfs_write_lock(s);
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ret = journal_begin(&th, s, bh_per_page + 1);
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if (ret)
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goto drop_write_lock;
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reiserfs_update_inode_transaction(inode);
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}
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for (bh = head = page_buffers(page), block_start = 0;
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bh != head || !block_start;
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block_start = block_end, bh = bh->b_this_page) {
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new = buffer_new(bh);
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clear_buffer_new(bh);
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block_end = block_start + blocksize;
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if (block_end <= from || block_start >= to) {
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if (!buffer_uptodate(bh))
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partial = 1;
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} else {
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set_buffer_uptodate(bh);
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if (logit) {
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reiserfs_prepare_for_journal(s, bh, 1);
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journal_mark_dirty(&th, bh);
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} else if (!buffer_dirty(bh)) {
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mark_buffer_dirty(bh);
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/*
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* do data=ordered on any page past the end
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* of file and any buffer marked BH_New.
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*/
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if (reiserfs_data_ordered(inode->i_sb) &&
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(new || page->index >= i_size_index)) {
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reiserfs_add_ordered_list(inode, bh);
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}
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}
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}
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}
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if (logit) {
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ret = journal_end(&th);
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drop_write_lock:
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reiserfs_write_unlock(s);
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}
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/*
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* If this is a partial write which happened to make all buffers
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* uptodate then we can optimize away a bogus read_folio() for
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* the next read(). Here we 'discover' whether the page went
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* uptodate as a result of this (potentially partial) write.
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*/
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if (!partial)
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SetPageUptodate(page);
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return ret;
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}
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const struct file_operations reiserfs_file_operations = {
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.unlocked_ioctl = reiserfs_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = reiserfs_compat_ioctl,
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#endif
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.mmap = generic_file_mmap,
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.open = reiserfs_file_open,
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.release = reiserfs_file_release,
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.fsync = reiserfs_sync_file,
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.read_iter = generic_file_read_iter,
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.write_iter = generic_file_write_iter,
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.splice_read = generic_file_splice_read,
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.splice_write = iter_file_splice_write,
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.llseek = generic_file_llseek,
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};
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const struct inode_operations reiserfs_file_inode_operations = {
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.setattr = reiserfs_setattr,
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.listxattr = reiserfs_listxattr,
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.permission = reiserfs_permission,
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.get_inode_acl = reiserfs_get_acl,
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.set_acl = reiserfs_set_acl,
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.fileattr_get = reiserfs_fileattr_get,
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.fileattr_set = reiserfs_fileattr_set,
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};
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