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Subject[PATCH 04/22][RFC] Unionfs: Common file operations
From: David Quigley <dquigley@fsl.cs.sunysb.edu>

This patch contains helper functions used through the rest of the code which
pertains to files.

Signed-off-by: David Quigley <dquigley@fsl.cs.sunysb.edu>
Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

---

fs/unionfs/commonfops.c | 575 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 575 insertions(+)

diff -Nur -x linux-2.6-git/Documentation/dontdiff linux-2.6-git/fs/unionfs/commonfops.c linux-2.6-git-unionfs/fs/unionfs/commonfops.c
--- linux-2.6-git/fs/unionfs/commonfops.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6-git-unionfs/fs/unionfs/commonfops.c 2006-08-31 19:04:00.000000000 -0400
@@ -0,0 +1,575 @@
+/*
+ * Copyright (c) 2003-2006 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2006 Josef 'Jeff' Sipek
+ * Copyright (c) 2005-2006 Junjiro Okajima
+ * Copyright (c) 2005 Arun M. Krishnakumar
+ * Copyright (c) 2004-2006 David P. Quigley
+ * Copyright (c) 2003-2004 Mohammad Nayyer Zubair
+ * Copyright (c) 2003 Puja Gupta
+ * Copyright (c) 2003 Harikesavan Krishnan
+ * Copyright (c) 2003-2006 Stony Brook University
+ * Copyright (c) 2003-2006 The Research Foundation of State University of New York
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package.
+ *
+ * This Copyright notice must be kept intact and distributed with all sources.
+ */
+
+#include "union.h"
+
+/* 1) Copyup the file
+ * 2) Rename the file to '.unionfs<original inode#><counter>' - obviously
+ * stolen from NFS's silly rename
+ */
+static int copyup_deleted_file(struct file *file, struct dentry *dentry,
+ int bstart, int bindex)
+{
+ static unsigned int counter;
+ const int i_inosize = sizeof(dentry->d_inode->i_ino) * 2;
+ const int countersize = sizeof(counter) * 2;
+ const int nlen = sizeof(".unionfs") + i_inosize + countersize - 1;
+ char name[nlen + 1];
+
+ int err;
+ struct dentry *tmp_dentry = NULL;
+ struct dentry *hidden_dentry = NULL;
+ struct dentry *hidden_dir_dentry = NULL;
+
+ hidden_dentry = dtohd_index(dentry, bstart);
+
+ sprintf(name, ".unionfs%*.*lx",
+ i_inosize, i_inosize, hidden_dentry->d_inode->i_ino);
+
+ tmp_dentry = NULL;
+ do {
+ char *suffix = name + nlen - countersize;
+
+ dput(tmp_dentry);
+ counter++;
+ sprintf(suffix, "%*.*x", countersize, countersize, counter);
+
+ printk(KERN_DEBUG "unionfs: trying to rename %s to %s\n",
+ dentry->d_name.name, name);
+
+ tmp_dentry = lookup_one_len(name, hidden_dentry->d_parent,
+ UNIONFS_TMPNAM_LEN);
+ if (IS_ERR(tmp_dentry)) {
+ err = PTR_ERR(tmp_dentry);
+ goto out;
+ }
+ } while (tmp_dentry->d_inode != NULL); /* need negative dentry */
+
+ err = copyup_named_file(dentry->d_parent->d_inode, file, name, bstart,
+ bindex, file->f_dentry->d_inode->i_size);
+ if (err)
+ goto out;
+
+ /* bring it to the same state as an unlinked file */
+ hidden_dentry = dtohd_index(dentry, dbstart(dentry));
+ hidden_dir_dentry = lock_parent(hidden_dentry);
+ err = vfs_unlink(hidden_dir_dentry->d_inode, hidden_dentry);
+ unlock_dir(hidden_dir_dentry);
+
+out:
+ return err;
+}
+
+static void cleanup_file(struct file *file, struct dentry *dentry)
+{
+ int bindex, bstart, bend;
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ if (ftohf_index(file, bindex)) {
+ branchput(dentry->d_sb, bindex);
+ fput(ftohf_index(file, bindex));
+ }
+ }
+
+ if (ftohf_ptr(file)) {
+ kfree(ftohf_ptr(file));
+ ftohf_ptr(file) = NULL;
+ }
+}
+
+static int open_all_files(struct file *file, struct dentry *dentry)
+{
+ int bindex, bstart, bend, err = 0;
+ struct file *hidden_file;
+ struct dentry *hidden_dentry;
+ struct super_block *sb = dentry->d_sb;
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry)
+ continue;
+
+ dget(hidden_dentry);
+ mntget(stohiddenmnt_index(sb, bindex));
+ branchget(sb, bindex);
+
+ hidden_file = dentry_open(hidden_dentry,
+ stohiddenmnt_index(sb, bindex), file->f_flags);
+ if (IS_ERR(hidden_file)) {
+ err = PTR_ERR(hidden_file);
+ goto out;
+ } else
+ set_ftohf_index(file, bindex, hidden_file);
+ }
+out:
+ return err;
+}
+
+static int open_highest_file(struct file *file, struct dentry *dentry,
+ int willwrite)
+{
+ int bindex, bstart, bend, err = 0;
+ struct file *hidden_file;
+ struct dentry *hidden_dentry;
+ struct inode *parent_inode = dentry->d_parent->d_inode;
+ size_t inode_size = file->f_dentry->d_inode->i_size;
+ struct super_block *sb = dentry->d_sb;
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+
+ hidden_dentry = dtohd(dentry);
+ if (willwrite && IS_WRITE_FLAG(file->f_flags)
+ && is_robranch(dentry)) {
+ for (bindex = bstart - 1; bindex >= 0; bindex--) {
+ err = copyup_file(parent_inode, file, bstart, bindex,
+ inode_size);
+ if (!err)
+ break;
+
+ }
+ atomic_set(&ftopd(file)->ufi_generation,
+ atomic_read(&itopd(dentry->d_inode)->uii_generation));
+ goto out;
+ }
+
+ dget(hidden_dentry);
+ mntget(stohiddenmnt_index(sb, bstart));
+ branchget(sb, bstart);
+ hidden_file = dentry_open(hidden_dentry,
+ stohiddenmnt_index(sb, bstart), file->f_flags);
+ if (IS_ERR(hidden_file)) {
+ err = PTR_ERR(hidden_file);
+ goto out;
+ }
+ set_ftohf(file, hidden_file);
+ /* Fix up the position. */
+ hidden_file->f_pos = file->f_pos;
+
+ memcpy(&(hidden_file->f_ra), &(file->f_ra),
+ sizeof(struct file_ra_state));
+out:
+ return err;
+}
+
+static int do_delayed_copyup(struct file *file, struct dentry *dentry)
+{
+ int bindex, bstart, bend, err = 0;
+ struct inode *parent_inode = dentry->d_parent->d_inode;
+ size_t inode_size = file->f_dentry->d_inode->i_size;
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+
+ BUG_ON(!S_ISREG(file->f_dentry->d_inode->i_mode));
+
+ for (bindex = bstart - 1; bindex >= 0; bindex--) {
+ if (!d_deleted(file->f_dentry))
+ err = copyup_file(parent_inode, file, bstart,
+ bindex, inode_size);
+ else
+ err = copyup_deleted_file(file, dentry, bstart, bindex);
+
+ if (!err)
+ break;
+ }
+ if (!err && (bstart > fbstart(file))) {
+ bend = fbend(file);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ if (ftohf_index(file, bindex)) {
+ branchput(dentry->d_sb, bindex);
+ fput(ftohf_index(file, bindex));
+ set_ftohf_index(file, bindex, NULL);
+ }
+ }
+ fbend(file) = bend;
+ }
+ return err;
+}
+
+int unionfs_file_revalidate(struct file *file, int willwrite)
+{
+ struct super_block *sb;
+ struct dentry *dentry;
+ int sbgen, fgen, dgen;
+ int bstart, bend;
+ int size;
+
+ int err = 0;
+
+ dentry = file->f_dentry;
+ lock_dentry(dentry);
+ sb = dentry->d_sb;
+ unionfs_read_lock(sb);
+ if (!unionfs_d_revalidate(dentry, NULL) && !d_deleted(dentry)) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ sbgen = atomic_read(&stopd(sb)->usi_generation);
+ dgen = atomic_read(&dtopd(dentry)->udi_generation);
+ fgen = atomic_read(&ftopd(file)->ufi_generation);
+
+ BUG_ON(sbgen > dgen);
+
+ /* There are two cases we are interested in. The first is if the
+ * generation is lower than the super-block. The second is if someone
+ * has copied up this file from underneath us, we also need to refresh
+ * things. */
+ if (!d_deleted(dentry) &&
+ ((sbgen > fgen) || (dbstart(dentry) != fbstart(file)))) {
+ /* First we throw out the existing files. */
+ cleanup_file(file, dentry);
+
+ /* Now we reopen the file(s) as in unionfs_open. */
+ bstart = fbstart(file) = dbstart(dentry);
+ bend = fbend(file) = dbend(dentry);
+
+ size = sizeof(struct file *) * sbmax(sb);
+ ftohf_ptr(file) = kzalloc(size, GFP_KERNEL);
+ if (!ftohf_ptr(file)) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ if (S_ISDIR(dentry->d_inode->i_mode)) {
+ /* We need to open all the files. */
+ err = open_all_files(file, dentry);
+ if (err)
+ goto out;
+ } else {
+ /* We only open the highest priority branch. */
+ err = open_highest_file(file, dentry, willwrite);
+ if (err)
+ goto out;
+ }
+ atomic_set(&ftopd(file)->ufi_generation,
+ atomic_read(&itopd(dentry->d_inode)->
+ uii_generation));
+ }
+
+ /* Copyup on the first write to a file on a readonly branch. */
+ if (willwrite && IS_WRITE_FLAG(file->f_flags)
+ && !IS_WRITE_FLAG(ftohf(file)->f_flags) && is_robranch(dentry)) {
+ printk(KERN_DEBUG
+ "Doing delayed copyup of a read-write file on a read-only branch.\n");
+ err = do_delayed_copyup(file, dentry);
+ }
+
+out:
+ unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+ return err;
+}
+
+/* unionfs_open helper function: open a directory */
+static inline int __open_dir(struct inode *inode, struct file *file)
+{
+ struct dentry *hidden_dentry;
+ struct file *hidden_file;
+ int bindex, bstart, bend;
+
+ bstart = fbstart(file) = dbstart(file->f_dentry);
+ bend = fbend(file) = dbend(file->f_dentry);
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry = dtohd_index(file->f_dentry, bindex);
+ if (!hidden_dentry)
+ continue;
+
+ dget(hidden_dentry);
+ mntget(stohiddenmnt_index(inode->i_sb, bindex));
+ hidden_file = dentry_open(hidden_dentry,
+ stohiddenmnt_index(inode->i_sb, bindex),
+ file->f_flags);
+ if (IS_ERR(hidden_file))
+ return PTR_ERR(hidden_file);
+
+ set_ftohf_index(file, bindex, hidden_file);
+
+ /* The branchget goes after the open, because otherwise
+ * we would miss the reference on release. */
+ branchget(inode->i_sb, bindex);
+ }
+
+ return 0;
+}
+
+/* unionfs_open helper function: open a file */
+static inline int __open_file(struct inode *inode, struct file *file)
+{
+ struct dentry *hidden_dentry;
+ struct file *hidden_file;
+ int hidden_flags;
+ int bindex, bstart, bend;
+
+ hidden_dentry = dtohd(file->f_dentry);
+ hidden_flags = file->f_flags;
+
+ bstart = fbstart(file) = dbstart(file->f_dentry);
+ bend = fbend(file) = dbend(file->f_dentry);
+
+ /* check for the permission for hidden file. If the error is COPYUP_ERR,
+ * copyup the file.
+ */
+ if (hidden_dentry->d_inode && is_robranch(file->f_dentry)) {
+ /* if the open will change the file, copy it up otherwise defer it. */
+ if (hidden_flags & O_TRUNC) {
+ int size = 0;
+ int err = -EROFS;
+
+ /* copyup the file */
+ for (bindex = bstart - 1; bindex >= 0; bindex--) {
+ err = copyup_file(file->f_dentry->d_parent->d_inode,
+ file, bstart, bindex, size);
+ if (!err)
+ break;
+ }
+ return err;
+ } else
+ hidden_flags &= ~(OPEN_WRITE_FLAGS);
+ }
+
+ dget(hidden_dentry);
+
+ /* dentry_open will decrement mnt refcnt if err.
+ * otherwise fput() will do an mntput() for us upon file close.
+ */
+ mntget(stohiddenmnt_index(inode->i_sb, bstart));
+ hidden_file = dentry_open(hidden_dentry,
+ stohiddenmnt_index(inode->i_sb, bstart),
+ hidden_flags);
+ if (IS_ERR(hidden_file))
+ return PTR_ERR(hidden_file);
+
+ set_ftohf(file, hidden_file);
+ branchget(inode->i_sb, bstart);
+
+ return 0;
+}
+
+int unionfs_open(struct inode *inode, struct file *file)
+{
+ int err = 0;
+ struct file *hidden_file = NULL;
+ struct dentry *dentry = NULL;
+ int bindex = 0, bstart = 0, bend = 0;
+ int size;
+
+ ftopd_lhs(file) = kzalloc(sizeof(struct unionfs_file_info), GFP_KERNEL);
+ if (!ftopd(file)) {
+ err = -ENOMEM;
+ goto out;
+ }
+ fbstart(file) = -1;
+ fbend(file) = -1;
+ atomic_set(&ftopd(file)->ufi_generation,
+ atomic_read(&itopd(inode)->uii_generation));
+
+ size = sizeof(struct file *) * sbmax(inode->i_sb);
+ ftohf_ptr(file) = kzalloc(size, GFP_KERNEL);
+ if (!ftohf_ptr(file)) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ dentry = file->f_dentry;
+ lock_dentry(dentry);
+ unionfs_read_lock(inode->i_sb);
+
+ bstart = fbstart(file) = dbstart(dentry);
+ bend = fbend(file) = dbend(dentry);
+
+ /* increment, so that we can flush appropriately */
+ atomic_inc(&itopd(dentry->d_inode)->uii_totalopens);
+
+ /* open all directories and make the unionfs file struct point to these hidden file structs */
+ if (S_ISDIR(inode->i_mode))
+ err = __open_dir(inode, file); /* open a dir */
+ else
+ err = __open_file(inode, file); /* open a file */
+
+ /* freeing the allocated resources, and fput the opened files */
+ if (err) {
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_file = ftohf_index(file, bindex);
+ if (!hidden_file)
+ continue;
+
+ branchput(file->f_dentry->d_sb, bindex);
+ /* fput calls dput for hidden_dentry */
+ fput(hidden_file);
+ }
+ }
+
+ unlock_dentry(dentry);
+ unionfs_read_unlock(inode->i_sb);
+
+out:
+ if (err) {
+ kfree(ftohf_ptr(file));
+ kfree(ftopd(file));
+ }
+
+ return err;
+}
+
+int unionfs_file_release(struct inode *inode, struct file *file)
+{
+ int err = 0;
+ struct file *hidden_file = NULL;
+ int bindex, bstart, bend;
+ int fgen;
+
+ /* fput all the hidden files */
+ fgen = atomic_read(&ftopd(file)->ufi_generation);
+ bstart = fbstart(file);
+ bend = fbend(file);
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_file = ftohf_index(file, bindex);
+
+ if (hidden_file) {
+ fput(hidden_file);
+ unionfs_read_lock(inode->i_sb);
+ branchput(inode->i_sb, bindex);
+ unionfs_read_unlock(inode->i_sb);
+ }
+ }
+ kfree(ftohf_ptr(file));
+
+ if (ftopd(file)->rdstate) {
+ ftopd(file)->rdstate->uds_access = jiffies;
+ printk(KERN_DEBUG "Saving rdstate with cookie %u [%d.%lld]\n",
+ ftopd(file)->rdstate->uds_cookie,
+ ftopd(file)->rdstate->uds_bindex,
+ (long long)ftopd(file)->rdstate->uds_dirpos);
+ spin_lock(&itopd(inode)->uii_rdlock);
+ itopd(inode)->uii_rdcount++;
+ list_add_tail(&ftopd(file)->rdstate->uds_cache,
+ &itopd(inode)->uii_readdircache);
+ mark_inode_dirty(inode);
+ spin_unlock(&itopd(inode)->uii_rdlock);
+ ftopd(file)->rdstate = NULL;
+ }
+ kfree(ftopd(file));
+ return err;
+}
+
+static inline long do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct file *hidden_file;
+ int err;
+
+ hidden_file = ftohf(file);
+
+ err = security_file_ioctl(hidden_file, cmd, arg);
+ if (err)
+ goto out;
+ err = -ENOTTY;
+ if (!hidden_file || !hidden_file->f_op)
+ goto out;
+ if (hidden_file->f_op->unlocked_ioctl) {
+ err = hidden_file->f_op->unlocked_ioctl(hidden_file, cmd, arg);
+ } else if (hidden_file->f_op->ioctl) {
+ lock_kernel();
+ err = hidden_file->f_op->ioctl(hidden_file->f_dentry->d_inode,
+ hidden_file, cmd, arg);
+ unlock_kernel();
+ }
+
+out:
+ return err;
+}
+
+long unionfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ long err = 0; /* don't fail by default */
+
+ if ((err = unionfs_file_revalidate(file, 1)))
+ goto out;
+
+ /* check if asked for local commands */
+ switch (cmd) {
+ case UNIONFS_IOCTL_INCGEN:
+ if (!capable(CAP_SYS_ADMIN)) {
+ err = -EACCES;
+ goto out;
+ }
+ err = unionfs_ioctl_incgen(file, cmd, arg);
+ break;
+
+ case UNIONFS_IOCTL_QUERYFILE:
+ err = unionfs_ioctl_queryfile(file, cmd, arg);
+ break;
+
+ default:
+ err = do_ioctl(file, cmd, arg);
+ break;
+ }
+
+out:
+ return err;
+}
+
+int unionfs_flush(struct file *file, fl_owner_t id)
+{
+ int err = 0; /* assume ok (see open.c:close_fp) */
+ struct file *hidden_file = NULL;
+ int bindex, bstart, bend;
+
+ if ((err = unionfs_file_revalidate(file, 1)))
+ goto out;
+ if (!atomic_dec_and_test
+ (&itopd(file->f_dentry->d_inode)->uii_totalopens))
+ goto out;
+
+ lock_dentry(file->f_dentry);
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_file = ftohf_index(file, bindex);
+
+ if (hidden_file && hidden_file->f_op
+ && hidden_file->f_op->flush) {
+ err = hidden_file->f_op->flush(hidden_file, id);
+ if (err)
+ goto out_lock;
+
+ /* if there are no more references to the dentry, dput it */
+ if (d_deleted(file->f_dentry)) {
+ dput(dtohd_index(file->f_dentry, bindex));
+ set_dtohd_index(file->f_dentry, bindex, NULL);
+ }
+ }
+
+ }
+
+out_lock:
+ unlock_dentry(file->f_dentry);
+out:
+ return err;
+}
+
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