| Message ID | 397ad80630444b90877625a1e94dd81392fc678e.1656531090.git.khalid.aziz@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add support for shared PTEs across processes | expand |
On Wed, Jun 29, 2022 at 04:53:54PM -0600, Khalid Aziz wrote: > Make msharefs filesystem writable and allow creating directories > to support better access control to mshare'd regions defined in > msharefs. > > Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> > --- > mm/mshare.c | 195 +++++++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 186 insertions(+), 9 deletions(-) > > diff --git a/mm/mshare.c b/mm/mshare.c > index 3e448e11c742..2d5924d39221 100644 > --- a/mm/mshare.c > +++ b/mm/mshare.c > @@ -21,11 +21,21 @@ > #include <linux/fileattr.h> > #include <uapi/linux/magic.h> > #include <uapi/linux/limits.h> > +#include <uapi/linux/mman.h> > > static struct super_block *msharefs_sb; > > +static const struct inode_operations msharefs_dir_inode_ops; > +static const struct inode_operations msharefs_file_inode_ops; > + > +static int > +msharefs_open(struct inode *inode, struct file *file) > +{ > + return simple_open(inode, file); > +} > + > static const struct file_operations msharefs_file_operations = { > - .open = simple_open, > + .open = msharefs_open, > .llseek = no_llseek, > }; > > @@ -42,6 +52,113 @@ msharefs_d_hash(const struct dentry *dentry, struct qstr *qstr) > return 0; > } > > +static struct dentry > +*msharefs_alloc_dentry(struct dentry *parent, const char *name) > +{ > + struct dentry *d; > + struct qstr q; > + int err; > + > + q.name = name; > + q.len = strlen(name); > + > + err = msharefs_d_hash(parent, &q); > + if (err) > + return ERR_PTR(err); > + > + d = d_alloc(parent, &q); > + if (d) > + return d; > + > + return ERR_PTR(-ENOMEM); > +} > + > +static struct inode > +*msharefs_get_inode(struct super_block *sb, const struct inode *dir, > + umode_t mode) > +{ > + struct inode *inode = new_inode(sb); > + > + if (inode) { Not sure why you wouldn't go with the less-indently version: if (!inode) return ERR_PTR(-ENOMEM); inode->i_ino = get_next_ino(); <etc> > + inode->i_ino = get_next_ino(); > + inode_init_owner(&init_user_ns, inode, dir, mode); > + > + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); > + > + switch (mode & S_IFMT) { Shouldn't we set the mode somewhere? > + case S_IFREG: > + inode->i_op = &msharefs_file_inode_ops; > + inode->i_fop = &msharefs_file_operations; > + break; > + case S_IFDIR: > + inode->i_op = &msharefs_dir_inode_ops; > + inode->i_fop = &simple_dir_operations; > + inc_nlink(inode); > + break; > + case S_IFLNK: > + inode->i_op = &page_symlink_inode_operations; > + break; > + default: > + discard_new_inode(inode); > + inode = NULL; > + break; > + } > + } > + > + return inode; > +} > + > +static int > +msharefs_mknod(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode, dev_t dev) > +{ > + struct inode *inode; > + int err = 0; > + > + inode = msharefs_get_inode(dir->i_sb, dir, mode); > + if (IS_ERR(inode)) > + return PTR_ERR(inode); ...and if @inode is NULL? > + > + d_instantiate(dentry, inode); > + dget(dentry); > + dir->i_mtime = dir->i_ctime = current_time(dir); > + > + return err; > +} > + > +static int > +msharefs_create(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode, bool excl) > +{ > + return msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); > +} > + > +static int > +msharefs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode) > +{ > + int ret = msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); > + > + if (!ret) > + inc_nlink(dir); > + return ret; > +} > + > +static const struct inode_operations msharefs_file_inode_ops = { > + .setattr = simple_setattr, > + .getattr = simple_getattr, > +}; > +static const struct inode_operations msharefs_dir_inode_ops = { > + .create = msharefs_create, > + .lookup = simple_lookup, > + .link = simple_link, > + .unlink = simple_unlink, > + .mkdir = msharefs_mkdir, > + .rmdir = simple_rmdir, > + .mknod = msharefs_mknod, > + .rename = simple_rename, > +}; > + > static void > mshare_evict_inode(struct inode *inode) > { > @@ -58,7 +175,7 @@ mshare_info_read(struct file *file, char __user *buf, size_t nbytes, > { > char s[80]; > > - sprintf(s, "%ld", PGDIR_SIZE); > + sprintf(s, "%ld\n", PGDIR_SIZE); Changing this already? > return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); > } > > @@ -72,6 +189,38 @@ static const struct super_operations mshare_s_ops = { > .evict_inode = mshare_evict_inode, > }; > > +static int > +prepopulate_files(struct super_block *s, struct inode *dir, > + struct dentry *root, const struct tree_descr *files) > +{ > + int i; > + struct inode *inode; > + struct dentry *dentry; > + > + for (i = 0; !files->name || files->name[0]; i++, files++) { > + if (!files->name) > + continue; What ends the array? NULL name or empty name? Do we have to erase all of these when the fs gets unmounted? --D > + > + dentry = msharefs_alloc_dentry(root, files->name); > + if (!dentry) > + return -ENOMEM; > + > + inode = msharefs_get_inode(s, dir, S_IFREG | files->mode); > + if (!inode) { > + dput(dentry); > + return -ENOMEM; > + } > + inode->i_mode = S_IFREG | files->mode; > + inode->i_atime = inode->i_mtime = inode->i_ctime > + = current_time(inode); > + inode->i_fop = files->ops; > + inode->i_ino = i; > + d_add(dentry, inode); > + } > + > + return 0; > +} > + > static int > msharefs_fill_super(struct super_block *sb, struct fs_context *fc) > { > @@ -79,21 +228,49 @@ msharefs_fill_super(struct super_block *sb, struct fs_context *fc) > [2] = { "mshare_info", &mshare_info_ops, 0444}, > {""}, > }; > - int err; > + struct inode *inode; > + struct dentry *root; > + int err = 0; > > - err = simple_fill_super(sb, MSHARE_MAGIC, mshare_files); > - if (!err) { > - msharefs_sb = sb; > - sb->s_d_op = &msharefs_d_ops; > - sb->s_op = &mshare_s_ops; > + sb->s_blocksize = PAGE_SIZE; > + sb->s_blocksize_bits = PAGE_SHIFT; > + sb->s_magic = MSHARE_MAGIC; > + sb->s_op = &mshare_s_ops; > + sb->s_d_op = &msharefs_d_ops; > + sb->s_time_gran = 1; > + > + inode = msharefs_get_inode(sb, NULL, S_IFDIR | 0777); > + if (!inode) { > + err = -ENOMEM; > + goto out; > } > + inode->i_ino = 1; > + root = d_make_root(inode); > + if (!root) { > + err = -ENOMEM; > + goto out; > + } > + > + err = prepopulate_files(sb, inode, root, mshare_files); > + if (err < 0) > + goto clean_root; > + > + sb->s_root = root; > + msharefs_sb = sb; > + return err; > + > +clean_root: > + d_genocide(root); > + shrink_dcache_parent(root); > + dput(root); > +out: > return err; > } > > static int > msharefs_get_tree(struct fs_context *fc) > { > - return get_tree_single(fc, msharefs_fill_super); > + return get_tree_nodev(fc, msharefs_fill_super); > } > > static const struct fs_context_operations msharefs_context_ops = { > -- > 2.32.0 >
On 6/30/22 15:34, Darrick J. Wong wrote: > On Wed, Jun 29, 2022 at 04:53:54PM -0600, Khalid Aziz wrote: >> Make msharefs filesystem writable and allow creating directories >> to support better access control to mshare'd regions defined in >> msharefs. >> >> Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> >> --- >> mm/mshare.c | 195 +++++++++++++++++++++++++++++++++++++++++++++++++--- >> 1 file changed, 186 insertions(+), 9 deletions(-) >> >> diff --git a/mm/mshare.c b/mm/mshare.c >> index 3e448e11c742..2d5924d39221 100644 >> --- a/mm/mshare.c >> +++ b/mm/mshare.c >> @@ -21,11 +21,21 @@ >> #include <linux/fileattr.h> >> #include <uapi/linux/magic.h> >> #include <uapi/linux/limits.h> >> +#include <uapi/linux/mman.h> >> >> static struct super_block *msharefs_sb; >> >> +static const struct inode_operations msharefs_dir_inode_ops; >> +static const struct inode_operations msharefs_file_inode_ops; >> + >> +static int >> +msharefs_open(struct inode *inode, struct file *file) >> +{ >> + return simple_open(inode, file); >> +} >> + >> static const struct file_operations msharefs_file_operations = { >> - .open = simple_open, >> + .open = msharefs_open, >> .llseek = no_llseek, >> }; >> >> @@ -42,6 +52,113 @@ msharefs_d_hash(const struct dentry *dentry, struct qstr *qstr) >> return 0; >> } >> >> +static struct dentry >> +*msharefs_alloc_dentry(struct dentry *parent, const char *name) >> +{ >> + struct dentry *d; >> + struct qstr q; >> + int err; >> + >> + q.name = name; >> + q.len = strlen(name); >> + >> + err = msharefs_d_hash(parent, &q); >> + if (err) >> + return ERR_PTR(err); >> + >> + d = d_alloc(parent, &q); >> + if (d) >> + return d; >> + >> + return ERR_PTR(-ENOMEM); >> +} >> + >> +static struct inode >> +*msharefs_get_inode(struct super_block *sb, const struct inode *dir, >> + umode_t mode) >> +{ >> + struct inode *inode = new_inode(sb); >> + >> + if (inode) { > > Not sure why you wouldn't go with the less-indently version: > > if (!inode) > return ERR_PTR(-ENOMEM); > > inode->i_ino = get_next_ino(); > <etc> > Yeah, good idea. I will change it. >> + inode->i_ino = get_next_ino(); >> + inode_init_owner(&init_user_ns, inode, dir, mode); >> + >> + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); >> + >> + switch (mode & S_IFMT) { > > Shouldn't we set the mode somewhere? mode is passed in as parameter to msharefs_get_inode() which uses this value to determine its actions. > >> + case S_IFREG: >> + inode->i_op = &msharefs_file_inode_ops; >> + inode->i_fop = &msharefs_file_operations; >> + break; >> + case S_IFDIR: >> + inode->i_op = &msharefs_dir_inode_ops; >> + inode->i_fop = &simple_dir_operations; >> + inc_nlink(inode); >> + break; >> + case S_IFLNK: >> + inode->i_op = &page_symlink_inode_operations; >> + break; >> + default: >> + discard_new_inode(inode); >> + inode = NULL; >> + break; >> + } >> + } >> + >> + return inode; >> +} >> + >> +static int >> +msharefs_mknod(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode, dev_t dev) >> +{ >> + struct inode *inode; >> + int err = 0; >> + >> + inode = msharefs_get_inode(dir->i_sb, dir, mode); >> + if (IS_ERR(inode)) >> + return PTR_ERR(inode); > > ...and if @inode is NULL? Oh right, IS_ERR() does not check for NULL value. I will add a check for that and return ENOMEM. > >> + >> + d_instantiate(dentry, inode); >> + dget(dentry); >> + dir->i_mtime = dir->i_ctime = current_time(dir); >> + >> + return err; >> +} >> + >> +static int >> +msharefs_create(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode, bool excl) >> +{ >> + return msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); >> +} >> + >> +static int >> +msharefs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode) >> +{ >> + int ret = msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); >> + >> + if (!ret) >> + inc_nlink(dir); >> + return ret; >> +} >> + >> +static const struct inode_operations msharefs_file_inode_ops = { >> + .setattr = simple_setattr, >> + .getattr = simple_getattr, >> +}; >> +static const struct inode_operations msharefs_dir_inode_ops = { >> + .create = msharefs_create, >> + .lookup = simple_lookup, >> + .link = simple_link, >> + .unlink = simple_unlink, >> + .mkdir = msharefs_mkdir, >> + .rmdir = simple_rmdir, >> + .mknod = msharefs_mknod, >> + .rename = simple_rename, >> +}; >> + >> static void >> mshare_evict_inode(struct inode *inode) >> { >> @@ -58,7 +175,7 @@ mshare_info_read(struct file *file, char __user *buf, size_t nbytes, >> { >> char s[80]; >> >> - sprintf(s, "%ld", PGDIR_SIZE); >> + sprintf(s, "%ld\n", PGDIR_SIZE); > > Changing this already? Possibly. There is one suggestion to change it to PMD and it might be a better choice. > >> return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); >> } >> >> @@ -72,6 +189,38 @@ static const struct super_operations mshare_s_ops = { >> .evict_inode = mshare_evict_inode, >> }; >> >> +static int >> +prepopulate_files(struct super_block *s, struct inode *dir, >> + struct dentry *root, const struct tree_descr *files) >> +{ >> + int i; >> + struct inode *inode; >> + struct dentry *dentry; >> + >> + for (i = 0; !files->name || files->name[0]; i++, files++) { >> + if (!files->name) >> + continue; > > What ends the array? NULL name or empty name? > Do we have to erase all of these when the fs gets unmounted? This code is very similar to simple_fill_super() and I reused the code from there. inodes and dentries will need to be erased on unmount through evict_inode. Thanks, Khalid
On Wed, Jun 29, 2022 at 04:53:54PM -0600, Khalid Aziz wrote: > +static int > +msharefs_open(struct inode *inode, struct file *file) > +{ > + return simple_open(inode, file); > +} Again, whatever for? > +static struct dentry > +*msharefs_alloc_dentry(struct dentry *parent, const char *name) > +{ > + struct dentry *d; > + struct qstr q; > + int err; > + > + q.name = name; > + q.len = strlen(name); > + > + err = msharefs_d_hash(parent, &q); > + if (err) > + return ERR_PTR(err); > + > + d = d_alloc(parent, &q); > + if (d) > + return d; > + > + return ERR_PTR(-ENOMEM); > +} And it's different from d_alloc_name() how, exactly? > + case S_IFLNK: > + inode->i_op = &page_symlink_inode_operations; > + break; Really? You've got symlinks here? > + default: > + discard_new_inode(inode); > + inode = NULL; That's an odd way to spell BUG()... > +static int > +msharefs_mknod(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode, dev_t dev) > +{ > + struct inode *inode; > + int err = 0; > + > + inode = msharefs_get_inode(dir->i_sb, dir, mode); > + if (IS_ERR(inode)) > + return PTR_ERR(inode); > + > + d_instantiate(dentry, inode); > + dget(dentry); > + dir->i_mtime = dir->i_ctime = current_time(dir); > + > + return err; > +} BTW, what's the point of having device nodes on that thing? > +static int > +msharefs_create(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode, bool excl) > +{ > + return msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); > +} > + > +static int > +msharefs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > + struct dentry *dentry, umode_t mode) > +{ > + int ret = msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); > + > + if (!ret) > + inc_nlink(dir); > + return ret; > +} > + > +static const struct inode_operations msharefs_file_inode_ops = { > + .setattr = simple_setattr, > + .getattr = simple_getattr, > +}; > +static const struct inode_operations msharefs_dir_inode_ops = { > + .create = msharefs_create, > + .lookup = simple_lookup, > + .link = simple_link, > + .unlink = simple_unlink, > + .mkdir = msharefs_mkdir, > + .rmdir = simple_rmdir, > + .mknod = msharefs_mknod, > + .rename = simple_rename, > +}; > + > static void > mshare_evict_inode(struct inode *inode) > { > @@ -58,7 +175,7 @@ mshare_info_read(struct file *file, char __user *buf, size_t nbytes, > { > char s[80]; > > - sprintf(s, "%ld", PGDIR_SIZE); > + sprintf(s, "%ld\n", PGDIR_SIZE); > return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); > } > > @@ -72,6 +189,38 @@ static const struct super_operations mshare_s_ops = { > .evict_inode = mshare_evict_inode, > }; > > +static int > +prepopulate_files(struct super_block *s, struct inode *dir, > + struct dentry *root, const struct tree_descr *files) > +{ > + int i; > + struct inode *inode; > + struct dentry *dentry; > + > + for (i = 0; !files->name || files->name[0]; i++, files++) { > + if (!files->name) > + continue; > + > + dentry = msharefs_alloc_dentry(root, files->name); > + if (!dentry) > + return -ENOMEM; > + > + inode = msharefs_get_inode(s, dir, S_IFREG | files->mode); > + if (!inode) { > + dput(dentry); > + return -ENOMEM; > + } > + inode->i_mode = S_IFREG | files->mode; > + inode->i_atime = inode->i_mtime = inode->i_ctime > + = current_time(inode); > + inode->i_fop = files->ops; > + inode->i_ino = i; > + d_add(dentry, inode); > + } > + > + return 0; > +} Looks remarkably similar to something I've seen somewhere... fs/libfs.c, if I'm not mistaken... Sarcasm aside, what's wrong with using simple_fill_super()?
On 6/30/22 17:09, Al Viro wrote: > On Wed, Jun 29, 2022 at 04:53:54PM -0600, Khalid Aziz wrote: > >> +static int >> +msharefs_open(struct inode *inode, struct file *file) >> +{ >> + return simple_open(inode, file); >> +} > > Again, whatever for? > >> +static struct dentry >> +*msharefs_alloc_dentry(struct dentry *parent, const char *name) >> +{ >> + struct dentry *d; >> + struct qstr q; >> + int err; >> + >> + q.name = name; >> + q.len = strlen(name); >> + >> + err = msharefs_d_hash(parent, &q); >> + if (err) >> + return ERR_PTR(err); >> + >> + d = d_alloc(parent, &q); >> + if (d) >> + return d; >> + >> + return ERR_PTR(-ENOMEM); >> +} > > And it's different from d_alloc_name() how, exactly? By making minor changes to my other code, I was able to use all of the standard functions you pointed out. That simplified my patch quite a bit. Thank you! > >> + case S_IFLNK: >> + inode->i_op = &page_symlink_inode_operations; >> + break; > > Really? You've got symlinks here? I intended to support symlinks on msharefs but I am not sure if I see a use case at this time. I can drop support for symlinks and add it in future if there is a use case. > >> + default: >> + discard_new_inode(inode); >> + inode = NULL; > > That's an odd way to spell BUG()... I think what you are saying is this default case represents a bug and I should report it as such. Is that right, or should I not have a default case at all (which is what I am seeing in some of the other places)? > >> +static int >> +msharefs_mknod(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode, dev_t dev) >> +{ >> + struct inode *inode; >> + int err = 0; >> + >> + inode = msharefs_get_inode(dir->i_sb, dir, mode); >> + if (IS_ERR(inode)) >> + return PTR_ERR(inode); >> + >> + d_instantiate(dentry, inode); >> + dget(dentry); >> + dir->i_mtime = dir->i_ctime = current_time(dir); >> + >> + return err; >> +} > > BTW, what's the point of having device nodes on that thing? There will be no device nodes on msharefs. Are you referring to the dev_t parameter in msharefs_mknod() declaration? If so, I am following the prototype declaration for that function from fs.h: int (*mknod) (struct user_namespace *, struct inode *,struct dentry *, umode_t,dev_t); If I am misunderstanding, please correct me. > >> +static int >> +msharefs_create(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode, bool excl) >> +{ >> + return msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); >> +} >> + >> +static int >> +msharefs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, >> + struct dentry *dentry, umode_t mode) >> +{ >> + int ret = msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); >> + >> + if (!ret) >> + inc_nlink(dir); >> + return ret; >> +} >> + >> +static const struct inode_operations msharefs_file_inode_ops = { >> + .setattr = simple_setattr, >> + .getattr = simple_getattr, >> +}; >> +static const struct inode_operations msharefs_dir_inode_ops = { >> + .create = msharefs_create, >> + .lookup = simple_lookup, >> + .link = simple_link, >> + .unlink = simple_unlink, >> + .mkdir = msharefs_mkdir, >> + .rmdir = simple_rmdir, >> + .mknod = msharefs_mknod, >> + .rename = simple_rename, >> +}; >> + >> static void >> mshare_evict_inode(struct inode *inode) >> { >> @@ -58,7 +175,7 @@ mshare_info_read(struct file *file, char __user *buf, size_t nbytes, >> { >> char s[80]; >> >> - sprintf(s, "%ld", PGDIR_SIZE); >> + sprintf(s, "%ld\n", PGDIR_SIZE); >> return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); >> } >> >> @@ -72,6 +189,38 @@ static const struct super_operations mshare_s_ops = { >> .evict_inode = mshare_evict_inode, >> }; >> >> +static int >> +prepopulate_files(struct super_block *s, struct inode *dir, >> + struct dentry *root, const struct tree_descr *files) >> +{ >> + int i; >> + struct inode *inode; >> + struct dentry *dentry; >> + >> + for (i = 0; !files->name || files->name[0]; i++, files++) { >> + if (!files->name) >> + continue; >> + >> + dentry = msharefs_alloc_dentry(root, files->name); >> + if (!dentry) >> + return -ENOMEM; >> + >> + inode = msharefs_get_inode(s, dir, S_IFREG | files->mode); >> + if (!inode) { >> + dput(dentry); >> + return -ENOMEM; >> + } >> + inode->i_mode = S_IFREG | files->mode; >> + inode->i_atime = inode->i_mtime = inode->i_ctime >> + = current_time(inode); >> + inode->i_fop = files->ops; >> + inode->i_ino = i; >> + d_add(dentry, inode); >> + } >> + >> + return 0; >> +} > > Looks remarkably similar to something I've seen somewhere... fs/libfs.c, > if I'm not mistaken... > > Sarcasm aside, what's wrong with using simple_fill_super()? I started out using simple_fill_super() in patch 1. I found that when I use simple_fill_super(), I end up with a filesystem that userspace can not create a file in. I looked at other code like shmfs and efivarfs and wrote similar code which got me a writable filesystem. I might be missing something basic and if there is a way to use simple_fill_super() and be able to support file creation from userspace, I would much rather use simple_fill_super(). Thanks, Khalid
diff --git a/mm/mshare.c b/mm/mshare.c index 3e448e11c742..2d5924d39221 100644 --- a/mm/mshare.c +++ b/mm/mshare.c @@ -21,11 +21,21 @@ #include <linux/fileattr.h> #include <uapi/linux/magic.h> #include <uapi/linux/limits.h> +#include <uapi/linux/mman.h> static struct super_block *msharefs_sb; +static const struct inode_operations msharefs_dir_inode_ops; +static const struct inode_operations msharefs_file_inode_ops; + +static int +msharefs_open(struct inode *inode, struct file *file) +{ + return simple_open(inode, file); +} + static const struct file_operations msharefs_file_operations = { - .open = simple_open, + .open = msharefs_open, .llseek = no_llseek, }; @@ -42,6 +52,113 @@ msharefs_d_hash(const struct dentry *dentry, struct qstr *qstr) return 0; } +static struct dentry +*msharefs_alloc_dentry(struct dentry *parent, const char *name) +{ + struct dentry *d; + struct qstr q; + int err; + + q.name = name; + q.len = strlen(name); + + err = msharefs_d_hash(parent, &q); + if (err) + return ERR_PTR(err); + + d = d_alloc(parent, &q); + if (d) + return d; + + return ERR_PTR(-ENOMEM); +} + +static struct inode +*msharefs_get_inode(struct super_block *sb, const struct inode *dir, + umode_t mode) +{ + struct inode *inode = new_inode(sb); + + if (inode) { + inode->i_ino = get_next_ino(); + inode_init_owner(&init_user_ns, inode, dir, mode); + + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + + switch (mode & S_IFMT) { + case S_IFREG: + inode->i_op = &msharefs_file_inode_ops; + inode->i_fop = &msharefs_file_operations; + break; + case S_IFDIR: + inode->i_op = &msharefs_dir_inode_ops; + inode->i_fop = &simple_dir_operations; + inc_nlink(inode); + break; + case S_IFLNK: + inode->i_op = &page_symlink_inode_operations; + break; + default: + discard_new_inode(inode); + inode = NULL; + break; + } + } + + return inode; +} + +static int +msharefs_mknod(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, dev_t dev) +{ + struct inode *inode; + int err = 0; + + inode = msharefs_get_inode(dir->i_sb, dir, mode); + if (IS_ERR(inode)) + return PTR_ERR(inode); + + d_instantiate(dentry, inode); + dget(dentry); + dir->i_mtime = dir->i_ctime = current_time(dir); + + return err; +} + +static int +msharefs_create(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) +{ + return msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); +} + +static int +msharefs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + int ret = msharefs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); + + if (!ret) + inc_nlink(dir); + return ret; +} + +static const struct inode_operations msharefs_file_inode_ops = { + .setattr = simple_setattr, + .getattr = simple_getattr, +}; +static const struct inode_operations msharefs_dir_inode_ops = { + .create = msharefs_create, + .lookup = simple_lookup, + .link = simple_link, + .unlink = simple_unlink, + .mkdir = msharefs_mkdir, + .rmdir = simple_rmdir, + .mknod = msharefs_mknod, + .rename = simple_rename, +}; + static void mshare_evict_inode(struct inode *inode) { @@ -58,7 +175,7 @@ mshare_info_read(struct file *file, char __user *buf, size_t nbytes, { char s[80]; - sprintf(s, "%ld", PGDIR_SIZE); + sprintf(s, "%ld\n", PGDIR_SIZE); return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); } @@ -72,6 +189,38 @@ static const struct super_operations mshare_s_ops = { .evict_inode = mshare_evict_inode, }; +static int +prepopulate_files(struct super_block *s, struct inode *dir, + struct dentry *root, const struct tree_descr *files) +{ + int i; + struct inode *inode; + struct dentry *dentry; + + for (i = 0; !files->name || files->name[0]; i++, files++) { + if (!files->name) + continue; + + dentry = msharefs_alloc_dentry(root, files->name); + if (!dentry) + return -ENOMEM; + + inode = msharefs_get_inode(s, dir, S_IFREG | files->mode); + if (!inode) { + dput(dentry); + return -ENOMEM; + } + inode->i_mode = S_IFREG | files->mode; + inode->i_atime = inode->i_mtime = inode->i_ctime + = current_time(inode); + inode->i_fop = files->ops; + inode->i_ino = i; + d_add(dentry, inode); + } + + return 0; +} + static int msharefs_fill_super(struct super_block *sb, struct fs_context *fc) { @@ -79,21 +228,49 @@ msharefs_fill_super(struct super_block *sb, struct fs_context *fc) [2] = { "mshare_info", &mshare_info_ops, 0444}, {""}, }; - int err; + struct inode *inode; + struct dentry *root; + int err = 0; - err = simple_fill_super(sb, MSHARE_MAGIC, mshare_files); - if (!err) { - msharefs_sb = sb; - sb->s_d_op = &msharefs_d_ops; - sb->s_op = &mshare_s_ops; + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = MSHARE_MAGIC; + sb->s_op = &mshare_s_ops; + sb->s_d_op = &msharefs_d_ops; + sb->s_time_gran = 1; + + inode = msharefs_get_inode(sb, NULL, S_IFDIR | 0777); + if (!inode) { + err = -ENOMEM; + goto out; } + inode->i_ino = 1; + root = d_make_root(inode); + if (!root) { + err = -ENOMEM; + goto out; + } + + err = prepopulate_files(sb, inode, root, mshare_files); + if (err < 0) + goto clean_root; + + sb->s_root = root; + msharefs_sb = sb; + return err; + +clean_root: + d_genocide(root); + shrink_dcache_parent(root); + dput(root); +out: return err; } static int msharefs_get_tree(struct fs_context *fc) { - return get_tree_single(fc, msharefs_fill_super); + return get_tree_nodev(fc, msharefs_fill_super); } static const struct fs_context_operations msharefs_context_ops = {
Make msharefs filesystem writable and allow creating directories to support better access control to mshare'd regions defined in msharefs. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> --- mm/mshare.c | 195 +++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 186 insertions(+), 9 deletions(-)