linux/fs/libfs.c

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/*
* fs/libfs.c
* Library for filesystems writers.
*/
#include <linux/module.h>
#include <linux/pagemap.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/vfs.h>
fs: introduce new truncate sequence Introduce a new truncate calling sequence into fs/mm subsystems. Rather than setattr > vmtruncate > truncate, have filesystems call their truncate sequence from ->setattr if filesystem specific operations are required. vmtruncate is deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced previously should be used. simple_setattr is introduced for simple in-ram filesystems to implement the new truncate sequence. Eventually all filesystems should be converted to implement a setattr, and the default code in notify_change should go away. simple_setsize is also introduced to perform just the ATTR_SIZE portion of simple_setattr (ie. changing i_size and trimming pagecache). To implement the new truncate sequence: - filesystem specific manipulations (eg freeing blocks) must be done in the setattr method rather than ->truncate. - vmtruncate can not be used by core code to trim blocks past i_size in the event of write failure after allocation, so this must be performed in the fs code. - convert usage of helpers block_write_begin, nobh_write_begin, cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed variants. These avoid calling vmtruncate to trim blocks (see previous). - inode_setattr should not be used. generic_setattr is a new function to be used to copy simple attributes into the generic inode. - make use of the better opportunity to handle errors with the new sequence. Big problem with the previous calling sequence: the filesystem is not called until i_size has already changed. This means it is not allowed to fail the call, and also it does not know what the previous i_size was. Also, generic code calling vmtruncate to truncate allocated blocks in case of error had no good way to return a meaningful error (or, for example, atomically handle block deallocation). Cc: Christoph Hellwig <hch@lst.de> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-26 15:05:33 +00:00
#include <linux/quotaops.h>
#include <linux/mutex.h>
#include <linux/exportfs.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <asm/uaccess.h>
int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat)
{
struct inode *inode = dentry->d_inode;
generic_fillattr(inode, stat);
stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
return 0;
}
int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
{
buf->f_type = dentry->d_sb->s_magic;
buf->f_bsize = PAGE_CACHE_SIZE;
buf->f_namelen = NAME_MAX;
return 0;
}
/*
* Retaining negative dentries for an in-memory filesystem just wastes
* memory and lookup time: arrange for them to be deleted immediately.
*/
static int simple_delete_dentry(struct dentry *dentry)
{
return 1;
}
/*
* Lookup the data. This is trivial - if the dentry didn't already
* exist, we know it is negative. Set d_op to delete negative dentries.
*/
struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
static const struct dentry_operations simple_dentry_operations = {
.d_delete = simple_delete_dentry,
};
if (dentry->d_name.len > NAME_MAX)
return ERR_PTR(-ENAMETOOLONG);
dentry->d_op = &simple_dentry_operations;
d_add(dentry, NULL);
return NULL;
}
int dcache_dir_open(struct inode *inode, struct file *file)
{
static struct qstr cursor_name = {.len = 1, .name = "."};
file->private_data = d_alloc(file->f_path.dentry, &cursor_name);
return file->private_data ? 0 : -ENOMEM;
}
int dcache_dir_close(struct inode *inode, struct file *file)
{
dput(file->private_data);
return 0;
}
loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
{
mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
switch (origin) {
case 1:
offset += file->f_pos;
case 0:
if (offset >= 0)
break;
default:
mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
return -EINVAL;
}
if (offset != file->f_pos) {
file->f_pos = offset;
if (file->f_pos >= 2) {
struct list_head *p;
struct dentry *cursor = file->private_data;
loff_t n = file->f_pos - 2;
spin_lock(&dcache_lock);
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
list_del(&cursor->d_u.d_child);
p = file->f_path.dentry->d_subdirs.next;
while (n && p != &file->f_path.dentry->d_subdirs) {
struct dentry *next;
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
next = list_entry(p, struct dentry, d_u.d_child);
if (!d_unhashed(next) && next->d_inode)
n--;
p = p->next;
}
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
list_add_tail(&cursor->d_u.d_child, p);
spin_unlock(&dcache_lock);
}
}
mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
return offset;
}
/* Relationship between i_mode and the DT_xxx types */
static inline unsigned char dt_type(struct inode *inode)
{
return (inode->i_mode >> 12) & 15;
}
/*
* Directory is locked and all positive dentries in it are safe, since
* for ramfs-type trees they can't go away without unlink() or rmdir(),
* both impossible due to the lock on directory.
*/
int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
struct dentry *dentry = filp->f_path.dentry;
struct dentry *cursor = filp->private_data;
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
struct list_head *p, *q = &cursor->d_u.d_child;
ino_t ino;
int i = filp->f_pos;
switch (i) {
case 0:
ino = dentry->d_inode->i_ino;
if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
i++;
/* fallthrough */
case 1:
ino = parent_ino(dentry);
if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
i++;
/* fallthrough */
default:
spin_lock(&dcache_lock);
if (filp->f_pos == 2)
list_move(q, &dentry->d_subdirs);
for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
struct dentry *next;
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
next = list_entry(p, struct dentry, d_u.d_child);
if (d_unhashed(next) || !next->d_inode)
continue;
spin_unlock(&dcache_lock);
if (filldir(dirent, next->d_name.name,
next->d_name.len, filp->f_pos,
next->d_inode->i_ino,
dt_type(next->d_inode)) < 0)
return 0;
spin_lock(&dcache_lock);
/* next is still alive */
list_move(q, p);
p = q;
filp->f_pos++;
}
spin_unlock(&dcache_lock);
}
return 0;
}
ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
{
return -EISDIR;
}
const struct file_operations simple_dir_operations = {
.open = dcache_dir_open,
.release = dcache_dir_close,
.llseek = dcache_dir_lseek,
.read = generic_read_dir,
.readdir = dcache_readdir,
.fsync = noop_fsync,
};
const struct inode_operations simple_dir_inode_operations = {
.lookup = simple_lookup,
};
static const struct super_operations simple_super_operations = {
.statfs = simple_statfs,
};
/*
* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
* will never be mountable)
*/
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
int get_sb_pseudo(struct file_system_type *fs_type, char *name,
const struct super_operations *ops, unsigned long magic,
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
struct vfsmount *mnt)
{
struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
struct dentry *dentry;
struct inode *root;
struct qstr d_name = {.name = name, .len = strlen(name)};
if (IS_ERR(s))
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
return PTR_ERR(s);
s->s_flags = MS_NOUSER;
s->s_maxbytes = MAX_LFS_FILESIZE;
s->s_blocksize = PAGE_SIZE;
s->s_blocksize_bits = PAGE_SHIFT;
s->s_magic = magic;
s->s_op = ops ? ops : &simple_super_operations;
s->s_time_gran = 1;
root = new_inode(s);
if (!root)
goto Enomem;
/*
* since this is the first inode, make it number 1. New inodes created
* after this must take care not to collide with it (by passing
* max_reserved of 1 to iunique).
*/
root->i_ino = 1;
root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
dentry = d_alloc(NULL, &d_name);
if (!dentry) {
iput(root);
goto Enomem;
}
dentry->d_sb = s;
dentry->d_parent = dentry;
d_instantiate(dentry, root);
s->s_root = dentry;
s->s_flags |= MS_ACTIVE;
simple_set_mnt(mnt, s);
return 0;
Enomem:
deactivate_locked_super(s);
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
return -ENOMEM;
}
int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
struct inode *inode = old_dentry->d_inode;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
inc_nlink(inode);
atomic_inc(&inode->i_count);
dget(dentry);
d_instantiate(dentry, inode);
return 0;
}
static inline int simple_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}
int simple_empty(struct dentry *dentry)
{
struct dentry *child;
int ret = 0;
spin_lock(&dcache_lock);
[PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 09:03:32 +00:00
list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
if (simple_positive(child))
goto out;
ret = 1;
out:
spin_unlock(&dcache_lock);
return ret;
}
int simple_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
drop_nlink(inode);
dput(dentry);
return 0;
}
int simple_rmdir(struct inode *dir, struct dentry *dentry)
{
if (!simple_empty(dentry))
return -ENOTEMPTY;
drop_nlink(dentry->d_inode);
simple_unlink(dir, dentry);
drop_nlink(dir);
return 0;
}
int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct inode *inode = old_dentry->d_inode;
int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
if (new_dentry->d_inode) {
simple_unlink(new_dir, new_dentry);
if (they_are_dirs)
drop_nlink(old_dir);
} else if (they_are_dirs) {
drop_nlink(old_dir);
inc_nlink(new_dir);
}
old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
return 0;
}
fs: introduce new truncate sequence Introduce a new truncate calling sequence into fs/mm subsystems. Rather than setattr > vmtruncate > truncate, have filesystems call their truncate sequence from ->setattr if filesystem specific operations are required. vmtruncate is deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced previously should be used. simple_setattr is introduced for simple in-ram filesystems to implement the new truncate sequence. Eventually all filesystems should be converted to implement a setattr, and the default code in notify_change should go away. simple_setsize is also introduced to perform just the ATTR_SIZE portion of simple_setattr (ie. changing i_size and trimming pagecache). To implement the new truncate sequence: - filesystem specific manipulations (eg freeing blocks) must be done in the setattr method rather than ->truncate. - vmtruncate can not be used by core code to trim blocks past i_size in the event of write failure after allocation, so this must be performed in the fs code. - convert usage of helpers block_write_begin, nobh_write_begin, cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed variants. These avoid calling vmtruncate to trim blocks (see previous). - inode_setattr should not be used. generic_setattr is a new function to be used to copy simple attributes into the generic inode. - make use of the better opportunity to handle errors with the new sequence. Big problem with the previous calling sequence: the filesystem is not called until i_size has already changed. This means it is not allowed to fail the call, and also it does not know what the previous i_size was. Also, generic code calling vmtruncate to truncate allocated blocks in case of error had no good way to return a meaningful error (or, for example, atomically handle block deallocation). Cc: Christoph Hellwig <hch@lst.de> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-26 15:05:33 +00:00
/**
* simple_setsize - handle core mm and vfs requirements for file size change
* @inode: inode
* @newsize: new file size
*
* Returns 0 on success, -error on failure.
*
* simple_setsize must be called with inode_mutex held.
*
* simple_setsize will check that the requested new size is OK (see
* inode_newsize_ok), and then will perform the necessary i_size update
* and pagecache truncation (if necessary). It will be typically be called
* from the filesystem's setattr function when ATTR_SIZE is passed in.
*
* The inode itself must have correct permissions and attributes to allow
* i_size to be changed, this function then just checks that the new size
* requested is valid.
*
* In the case of simple in-memory filesystems with inodes stored solely
* in the inode cache, and file data in the pagecache, nothing more needs
* to be done to satisfy a truncate request. Filesystems with on-disk
* blocks for example will need to free them in the case of truncate, in
* that case it may be easier not to use simple_setsize (but each of its
* components will likely be required at some point to update pagecache
* and inode etc).
*/
int simple_setsize(struct inode *inode, loff_t newsize)
{
loff_t oldsize;
int error;
error = inode_newsize_ok(inode, newsize);
if (error)
return error;
oldsize = inode->i_size;
i_size_write(inode, newsize);
truncate_pagecache(inode, oldsize, newsize);
return error;
}
EXPORT_SYMBOL(simple_setsize);
/**
* simple_setattr - setattr for simple in-memory filesystem
* @dentry: dentry
* @iattr: iattr structure
*
* Returns 0 on success, -error on failure.
*
* simple_setattr implements setattr for an in-memory filesystem which
* does not store its own file data or metadata (eg. uses the page cache
* and inode cache as its data store).
*/
int simple_setattr(struct dentry *dentry, struct iattr *iattr)
{
struct inode *inode = dentry->d_inode;
int error;
error = inode_change_ok(inode, iattr);
if (error)
return error;
if (iattr->ia_valid & ATTR_SIZE) {
error = simple_setsize(inode, iattr->ia_size);
if (error)
return error;
}
generic_setattr(inode, iattr);
return error;
}
EXPORT_SYMBOL(simple_setattr);
int simple_readpage(struct file *file, struct page *page)
{
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
unlock_page(page);
return 0;
}
int simple_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
struct page *page;
pgoff_t index;
index = pos >> PAGE_CACHE_SHIFT;
fs: symlink write_begin allocation context fix With the write_begin/write_end aops, page_symlink was broken because it could no longer pass a GFP_NOFS type mask into the point where the allocations happened. They are done in write_begin, which would always assume that the filesystem can be entered from reclaim. This bug could cause filesystem deadlocks. The funny thing with having a gfp_t mask there is that it doesn't really allow the caller to arbitrarily tinker with the context in which it can be called. It couldn't ever be GFP_ATOMIC, for example, because it needs to take the page lock. The only thing any callers care about is __GFP_FS anyway, so turn that into a single flag. Add a new flag for write_begin, AOP_FLAG_NOFS. Filesystems can now act on this flag in their write_begin function. Change __grab_cache_page to accept a nofs argument as well, to honour that flag (while we're there, change the name to grab_cache_page_write_begin which is more instructive and does away with random leading underscores). This is really a more flexible way to go in the end anyway -- if a filesystem happens to want any extra allocations aside from the pagecache ones in ints write_begin function, it may now use GFP_KERNEL (rather than GFP_NOFS) for common case allocations (eg. ocfs2_alloc_write_ctxt, for a random example). [kosaki.motohiro@jp.fujitsu.com: fix ubifs] [kosaki.motohiro@jp.fujitsu.com: fix fuse] Signed-off-by: Nick Piggin <npiggin@suse.de> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: <stable@kernel.org> [2.6.28.x] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Cleaned up the calling convention: just pass in the AOP flags untouched to the grab_cache_page_write_begin() function. That just simplifies everybody, and may even allow future expansion of the logic. - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-04 20:00:53 +00:00
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
*pagep = page;
if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE);
}
return 0;
}
/**
* simple_write_end - .write_end helper for non-block-device FSes
* @available: See .write_end of address_space_operations
* @file: "
* @mapping: "
* @pos: "
* @len: "
* @copied: "
* @page: "
* @fsdata: "
*
* simple_write_end does the minimum needed for updating a page after writing is
* done. It has the same API signature as the .write_end of
* address_space_operations vector. So it can just be set onto .write_end for
* FSes that don't need any other processing. i_mutex is assumed to be held.
* Block based filesystems should use generic_write_end().
* NOTE: Even though i_size might get updated by this function, mark_inode_dirty
* is not called, so a filesystem that actually does store data in .write_inode
* should extend on what's done here with a call to mark_inode_dirty() in the
* case that i_size has changed.
*/
int simple_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
struct inode *inode = page->mapping->host;
loff_t last_pos = pos + copied;
/* zero the stale part of the page if we did a short copy */
if (copied < len) {
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
zero_user(page, from + copied, len - copied);
}
if (!PageUptodate(page))
SetPageUptodate(page);
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold the i_mutex.
*/
if (last_pos > inode->i_size)
i_size_write(inode, last_pos);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
return copied;
}
/*
* the inodes created here are not hashed. If you use iunique to generate
* unique inode values later for this filesystem, then you must take care
* to pass it an appropriate max_reserved value to avoid collisions.
*/
int simple_fill_super(struct super_block *s, unsigned long magic,
struct tree_descr *files)
{
struct inode *inode;
struct dentry *root;
struct dentry *dentry;
int i;
s->s_blocksize = PAGE_CACHE_SIZE;
s->s_blocksize_bits = PAGE_CACHE_SHIFT;
s->s_magic = magic;
s->s_op = &simple_super_operations;
s->s_time_gran = 1;
inode = new_inode(s);
if (!inode)
return -ENOMEM;
/*
* because the root inode is 1, the files array must not contain an
* entry at index 1
*/
inode->i_ino = 1;
inode->i_mode = S_IFDIR | 0755;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_nlink = 2;
root = d_alloc_root(inode);
if (!root) {
iput(inode);
return -ENOMEM;
}
for (i = 0; !files->name || files->name[0]; i++, files++) {
if (!files->name)
continue;
/* warn if it tries to conflict with the root inode */
if (unlikely(i == 1))
printk(KERN_WARNING "%s: %s passed in a files array"
"with an index of 1!\n", __func__,
s->s_type->name);
dentry = d_alloc_name(root, files->name);
if (!dentry)
goto out;
inode = new_inode(s);
if (!inode)
goto out;
inode->i_mode = S_IFREG | files->mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_fop = files->ops;
inode->i_ino = i;
d_add(dentry, inode);
}
s->s_root = root;
return 0;
out:
d_genocide(root);
dput(root);
return -ENOMEM;
}
static DEFINE_SPINLOCK(pin_fs_lock);
int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
{
struct vfsmount *mnt = NULL;
spin_lock(&pin_fs_lock);
if (unlikely(!*mount)) {
spin_unlock(&pin_fs_lock);
mnt = vfs_kern_mount(type, 0, type->name, NULL);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
spin_lock(&pin_fs_lock);
if (!*mount)
*mount = mnt;
}
mntget(*mount);
++*count;
spin_unlock(&pin_fs_lock);
mntput(mnt);
return 0;
}
void simple_release_fs(struct vfsmount **mount, int *count)
{
struct vfsmount *mnt;
spin_lock(&pin_fs_lock);
mnt = *mount;
if (!--*count)
*mount = NULL;
spin_unlock(&pin_fs_lock);
mntput(mnt);
}
/**
* simple_read_from_buffer - copy data from the buffer to user space
* @to: the user space buffer to read to
* @count: the maximum number of bytes to read
* @ppos: the current position in the buffer
* @from: the buffer to read from
* @available: the size of the buffer
*
* The simple_read_from_buffer() function reads up to @count bytes from the
* buffer @from at offset @ppos into the user space address starting at @to.
*
* On success, the number of bytes read is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
const void *from, size_t available)
{
loff_t pos = *ppos;
size_t ret;
if (pos < 0)
return -EINVAL;
if (pos >= available || !count)
return 0;
if (count > available - pos)
count = available - pos;
ret = copy_to_user(to, from + pos, count);
if (ret == count)
return -EFAULT;
count -= ret;
*ppos = pos + count;
return count;
}
/**
* simple_write_to_buffer - copy data from user space to the buffer
* @to: the buffer to write to
* @available: the size of the buffer
* @ppos: the current position in the buffer
* @from: the user space buffer to read from
* @count: the maximum number of bytes to read
*
* The simple_write_to_buffer() function reads up to @count bytes from the user
* space address starting at @from into the buffer @to at offset @ppos.
*
* On success, the number of bytes written is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
const void __user *from, size_t count)
{
loff_t pos = *ppos;
size_t res;
if (pos < 0)
return -EINVAL;
if (pos >= available || !count)
return 0;
if (count > available - pos)
count = available - pos;
res = copy_from_user(to + pos, from, count);
if (res == count)
return -EFAULT;
count -= res;
*ppos = pos + count;
return count;
}
/**
* memory_read_from_buffer - copy data from the buffer
* @to: the kernel space buffer to read to
* @count: the maximum number of bytes to read
* @ppos: the current position in the buffer
* @from: the buffer to read from
* @available: the size of the buffer
*
* The memory_read_from_buffer() function reads up to @count bytes from the
* buffer @from at offset @ppos into the kernel space address starting at @to.
*
* On success, the number of bytes read is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
2008-06-06 05:46:21 +00:00
ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
const void *from, size_t available)
{
loff_t pos = *ppos;
if (pos < 0)
return -EINVAL;
if (pos >= available)
return 0;
if (count > available - pos)
count = available - pos;
memcpy(to, from + pos, count);
*ppos = pos + count;
return count;
}
/*
* Transaction based IO.
* The file expects a single write which triggers the transaction, and then
* possibly a read which collects the result - which is stored in a
* file-local buffer.
*/
void simple_transaction_set(struct file *file, size_t n)
{
struct simple_transaction_argresp *ar = file->private_data;
BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
/*
* The barrier ensures that ar->size will really remain zero until
* ar->data is ready for reading.
*/
smp_mb();
ar->size = n;
}
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
{
struct simple_transaction_argresp *ar;
static DEFINE_SPINLOCK(simple_transaction_lock);
if (size > SIMPLE_TRANSACTION_LIMIT - 1)
return ERR_PTR(-EFBIG);
ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
if (!ar)
return ERR_PTR(-ENOMEM);
spin_lock(&simple_transaction_lock);
/* only one write allowed per open */
if (file->private_data) {
spin_unlock(&simple_transaction_lock);
free_page((unsigned long)ar);
return ERR_PTR(-EBUSY);
}
file->private_data = ar;
spin_unlock(&simple_transaction_lock);
if (copy_from_user(ar->data, buf, size))
return ERR_PTR(-EFAULT);
return ar->data;
}
ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
{
struct simple_transaction_argresp *ar = file->private_data;
if (!ar)
return 0;
return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
}
int simple_transaction_release(struct inode *inode, struct file *file)
{
free_page((unsigned long)file->private_data);
return 0;
}
/* Simple attribute files */
struct simple_attr {
int (*get)(void *, u64 *);
int (*set)(void *, u64);
char get_buf[24]; /* enough to store a u64 and "\n\0" */
char set_buf[24];
void *data;
const char *fmt; /* format for read operation */
struct mutex mutex; /* protects access to these buffers */
};
/* simple_attr_open is called by an actual attribute open file operation
* to set the attribute specific access operations. */
int simple_attr_open(struct inode *inode, struct file *file,
int (*get)(void *, u64 *), int (*set)(void *, u64),
const char *fmt)
{
struct simple_attr *attr;
attr = kmalloc(sizeof(*attr), GFP_KERNEL);
if (!attr)
return -ENOMEM;
attr->get = get;
attr->set = set;
attr->data = inode->i_private;
attr->fmt = fmt;
mutex_init(&attr->mutex);
file->private_data = attr;
return nonseekable_open(inode, file);
}
int simple_attr_release(struct inode *inode, struct file *file)
{
kfree(file->private_data);
return 0;
}
/* read from the buffer that is filled with the get function */
ssize_t simple_attr_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
struct simple_attr *attr;
size_t size;
ssize_t ret;
attr = file->private_data;
if (!attr->get)
return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex);
if (ret)
return ret;
if (*ppos) { /* continued read */
size = strlen(attr->get_buf);
} else { /* first read */
u64 val;
ret = attr->get(attr->data, &val);
if (ret)
goto out;
size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
attr->fmt, (unsigned long long)val);
}
ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
out:
mutex_unlock(&attr->mutex);
return ret;
}
/* interpret the buffer as a number to call the set function with */
ssize_t simple_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
struct simple_attr *attr;
u64 val;
size_t size;
ssize_t ret;
attr = file->private_data;
if (!attr->set)
return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex);
if (ret)
return ret;
ret = -EFAULT;
size = min(sizeof(attr->set_buf) - 1, len);
if (copy_from_user(attr->set_buf, buf, size))
goto out;
attr->set_buf[size] = '\0';
val = simple_strtol(attr->set_buf, NULL, 0);
ret = attr->set(attr->data, val);
if (ret == 0)
ret = len; /* on success, claim we got the whole input */
out:
mutex_unlock(&attr->mutex);
return ret;
}
/**
* generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
* @sb: filesystem to do the file handle conversion on
* @fid: file handle to convert
* @fh_len: length of the file handle in bytes
* @fh_type: type of file handle
* @get_inode: filesystem callback to retrieve inode
*
* This function decodes @fid as long as it has one of the well-known
* Linux filehandle types and calls @get_inode on it to retrieve the
* inode for the object specified in the file handle.
*/
struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type, struct inode *(*get_inode)
(struct super_block *sb, u64 ino, u32 gen))
{
struct inode *inode = NULL;
if (fh_len < 2)
return NULL;
switch (fh_type) {
case FILEID_INO32_GEN:
case FILEID_INO32_GEN_PARENT:
inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
break;
}
return d_obtain_alias(inode);
}
EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
/**
* generic_fh_to_dentry - generic helper for the fh_to_parent export operation
* @sb: filesystem to do the file handle conversion on
* @fid: file handle to convert
* @fh_len: length of the file handle in bytes
* @fh_type: type of file handle
* @get_inode: filesystem callback to retrieve inode
*
* This function decodes @fid as long as it has one of the well-known
* Linux filehandle types and calls @get_inode on it to retrieve the
* inode for the _parent_ object specified in the file handle if it
* is specified in the file handle, or NULL otherwise.
*/
struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type, struct inode *(*get_inode)
(struct super_block *sb, u64 ino, u32 gen))
{
struct inode *inode = NULL;
if (fh_len <= 2)
return NULL;
switch (fh_type) {
case FILEID_INO32_GEN_PARENT:
inode = get_inode(sb, fid->i32.parent_ino,
(fh_len > 3 ? fid->i32.parent_gen : 0));
break;
}
return d_obtain_alias(inode);
}
EXPORT_SYMBOL_GPL(generic_fh_to_parent);
/**
* generic_file_fsync - generic fsync implementation for simple filesystems
* @file: file to synchronize
* @datasync: only synchronize essential metadata if true
*
* This is a generic implementation of the fsync method for simple
* filesystems which track all non-inode metadata in the buffers list
* hanging off the address_space structure.
*/
int generic_file_fsync(struct file *file, int datasync)
{
struct writeback_control wbc = {
.sync_mode = WB_SYNC_ALL,
.nr_to_write = 0, /* metadata-only; caller takes care of data */
};
struct inode *inode = file->f_mapping->host;
int err;
int ret;
ret = sync_mapping_buffers(inode->i_mapping);
if (!(inode->i_state & I_DIRTY))
return ret;
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
return ret;
err = sync_inode(inode, &wbc);
if (ret == 0)
ret = err;
return ret;
}
EXPORT_SYMBOL(generic_file_fsync);
/*
* No-op implementation of ->fsync for in-memory filesystems.
*/
int noop_fsync(struct file *file, int datasync)
{
return 0;
}
EXPORT_SYMBOL(dcache_dir_close);
EXPORT_SYMBOL(dcache_dir_lseek);
EXPORT_SYMBOL(dcache_dir_open);
EXPORT_SYMBOL(dcache_readdir);
EXPORT_SYMBOL(generic_read_dir);
EXPORT_SYMBOL(get_sb_pseudo);
EXPORT_SYMBOL(simple_write_begin);
EXPORT_SYMBOL(simple_write_end);
EXPORT_SYMBOL(simple_dir_inode_operations);
EXPORT_SYMBOL(simple_dir_operations);
EXPORT_SYMBOL(simple_empty);
EXPORT_SYMBOL(simple_fill_super);
EXPORT_SYMBOL(simple_getattr);
EXPORT_SYMBOL(simple_link);
EXPORT_SYMBOL(simple_lookup);
EXPORT_SYMBOL(simple_pin_fs);
EXPORT_SYMBOL(simple_readpage);
EXPORT_SYMBOL(simple_release_fs);
EXPORT_SYMBOL(simple_rename);
EXPORT_SYMBOL(simple_rmdir);
EXPORT_SYMBOL(simple_statfs);
EXPORT_SYMBOL(noop_fsync);
EXPORT_SYMBOL(simple_unlink);
EXPORT_SYMBOL(simple_read_from_buffer);
EXPORT_SYMBOL(simple_write_to_buffer);
2008-06-06 05:46:21 +00:00
EXPORT_SYMBOL(memory_read_from_buffer);
EXPORT_SYMBOL(simple_transaction_set);
EXPORT_SYMBOL(simple_transaction_get);
EXPORT_SYMBOL(simple_transaction_read);
EXPORT_SYMBOL(simple_transaction_release);
EXPORT_SYMBOL_GPL(simple_attr_open);
EXPORT_SYMBOL_GPL(simple_attr_release);
EXPORT_SYMBOL_GPL(simple_attr_read);
EXPORT_SYMBOL_GPL(simple_attr_write);