deal with races in /proc/*/{syscall,stack,personality}

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / jfs / xattr.c

/*
 *   Copyright (C) International Business Machines  Corp., 2000-2004
 *   Copyright (C) Christoph Hellwig, 2002
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/quotaops.h>
#include <linux/security.h>
#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_dmap.h"
#include "jfs_debug.h"
#include "jfs_dinode.h"
#include "jfs_extent.h"
#include "jfs_metapage.h"
#include "jfs_xattr.h"
#include "jfs_acl.h"

/*
 *      jfs_xattr.c: extended attribute service
 *
 * Overall design --
 *
 * Format:
 *
 *   Extended attribute lists (jfs_ea_list) consist of an overall size (32 bit
 *   value) and a variable (0 or more) number of extended attribute
 *   entries.  Each extended attribute entry (jfs_ea) is a <name,value> double
 *   where <name> is constructed from a null-terminated ascii string
 *   (1 ... 255 bytes in the name) and <value> is arbitrary 8 bit data
 *   (1 ... 65535 bytes).  The in-memory format is
 *
 *   0       1        2        4                4 + namelen + 1
 *   +-------+--------+--------+----------------+-------------------+
 *   | Flags | Name   | Value  | Name String \0 | Data . . . .      |
 *   |       | Length | Length |                |                   |
 *   +-------+--------+--------+----------------+-------------------+
 *
 *   A jfs_ea_list then is structured as
 *
 *   0            4                   4 + EA_SIZE(ea1)
 *   +------------+-------------------+--------------------+-----
 *   | Overall EA | First FEA Element | Second FEA Element | .....
 *   | List Size  |                   |                    |
 *   +------------+-------------------+--------------------+-----
 *
 *   On-disk:
 *
 *      FEALISTs are stored on disk using blocks allocated by dbAlloc() and
 *      written directly. An EA list may be in-lined in the inode if there is
 *      sufficient room available.
 */

struct ea_buffer {
        int flag;               /* Indicates what storage xattr points to */
        int max_size;           /* largest xattr that fits in current buffer */
        dxd_t new_ea;           /* dxd to replace ea when modifying xattr */
        struct metapage *mp;    /* metapage containing ea list */
        struct jfs_ea_list *xattr;      /* buffer containing ea list */
};

/*
 * ea_buffer.flag values
 */
#define EA_INLINE       0x0001
#define EA_EXTENT       0x0002
#define EA_NEW          0x0004
#define EA_MALLOC       0x0008


static int is_known_namespace(const char *name)
{
        if (strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) &&
            strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
            strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) &&
            strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
                return false;

        return true;
}

/*
 * These three routines are used to recognize on-disk extended attributes
 * that are in a recognized namespace.  If the attribute is not recognized,
 * "os2." is prepended to the name
 */
static int is_os2_xattr(struct jfs_ea *ea)
{
        return !is_known_namespace(ea->name);
}

static inline int name_size(struct jfs_ea *ea)
{
        if (is_os2_xattr(ea))
                return ea->namelen + XATTR_OS2_PREFIX_LEN;
        else
                return ea->namelen;
}

static inline int copy_name(char *buffer, struct jfs_ea *ea)
{
        int len = ea->namelen;

        if (is_os2_xattr(ea)) {
                memcpy(buffer, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN);
                buffer += XATTR_OS2_PREFIX_LEN;
                len += XATTR_OS2_PREFIX_LEN;
        }
        memcpy(buffer, ea->name, ea->namelen);
        buffer[ea->namelen] = 0;

        return len;
}

/* Forward references */
static void ea_release(struct inode *inode, struct ea_buffer *ea_buf);

/*
 * NAME: ea_write_inline
 *
 * FUNCTION: Attempt to write an EA inline if area is available
 *
 * PRE CONDITIONS:
 *      Already verified that the specified EA is small enough to fit inline
 *
 * PARAMETERS:
 *      ip      - Inode pointer
 *      ealist  - EA list pointer
 *      size    - size of ealist in bytes
 *      ea      - dxd_t structure to be filled in with necessary EA information
 *                if we successfully copy the EA inline
 *
 * NOTES:
 *      Checks if the inode's inline area is available.  If so, copies EA inline
 *      and sets <ea> fields appropriately.  Otherwise, returns failure, EA will
 *      have to be put into an extent.
 *
 * RETURNS: 0 for successful copy to inline area; -1 if area not available
 */
static int ea_write_inline(struct inode *ip, struct jfs_ea_list *ealist,
                           int size, dxd_t * ea)
{
        struct jfs_inode_info *ji = JFS_IP(ip);

        /*
         * Make sure we have an EA -- the NULL EA list is valid, but you
         * can't copy it!
         */
        if (ealist && size > sizeof (struct jfs_ea_list)) {
                assert(size <= sizeof (ji->i_inline_ea));

                /*
                 * See if the space is available or if it is already being
                 * used for an inline EA.
                 */
                if (!(ji->mode2 & INLINEEA) && !(ji->ea.flag & DXD_INLINE))
                        return -EPERM;

                DXDsize(ea, size);
                DXDlength(ea, 0);
                DXDaddress(ea, 0);
                memcpy(ji->i_inline_ea, ealist, size);
                ea->flag = DXD_INLINE;
                ji->mode2 &= ~INLINEEA;
        } else {
                ea->flag = 0;
                DXDsize(ea, 0);
                DXDlength(ea, 0);
                DXDaddress(ea, 0);

                /* Free up INLINE area */
                if (ji->ea.flag & DXD_INLINE)
                        ji->mode2 |= INLINEEA;
        }

        return 0;
}

/*
 * NAME: ea_write
 *
 * FUNCTION: Write an EA for an inode
 *
 * PRE CONDITIONS: EA has been verified
 *
 * PARAMETERS:
 *      ip      - Inode pointer
 *      ealist  - EA list pointer
 *      size    - size of ealist in bytes
 *      ea      - dxd_t structure to be filled in appropriately with where the
 *                EA was copied
 *
 * NOTES: Will write EA inline if able to, otherwise allocates blocks for an
 *      extent and synchronously writes it to those blocks.
 *
 * RETURNS: 0 for success; Anything else indicates failure
 */
static int ea_write(struct inode *ip, struct jfs_ea_list *ealist, int size,
                       dxd_t * ea)
{
        struct super_block *sb = ip->i_sb;
        struct jfs_inode_info *ji = JFS_IP(ip);
        struct jfs_sb_info *sbi = JFS_SBI(sb);
        int nblocks;
        s64 blkno;
        int rc = 0, i;
        char *cp;
        s32 nbytes, nb;
        s32 bytes_to_write;
        struct metapage *mp;

        /*
         * Quick check to see if this is an in-linable EA.  Short EAs
         * and empty EAs are all in-linable, provided the space exists.
         */
        if (!ealist || size <= sizeof (ji->i_inline_ea)) {
                if (!ea_write_inline(ip, ealist, size, ea))
                        return 0;
        }

        /* figure out how many blocks we need */
        nblocks = (size + (sb->s_blocksize - 1)) >> sb->s_blocksize_bits;

        /* Allocate new blocks to quota. */
        if (vfs_dq_alloc_block(ip, nblocks)) {
                return -EDQUOT;
        }

        rc = dbAlloc(ip, INOHINT(ip), nblocks, &blkno);
        if (rc) {
                /*Rollback quota allocation. */
                vfs_dq_free_block(ip, nblocks);
                return rc;
        }

        /*
         * Now have nblocks worth of storage to stuff into the FEALIST.
         * loop over the FEALIST copying data into the buffer one page at
         * a time.
         */
        cp = (char *) ealist;
        nbytes = size;
        for (i = 0; i < nblocks; i += sbi->nbperpage) {
                /*
                 * Determine how many bytes for this request, and round up to
                 * the nearest aggregate block size
                 */
                nb = min(PSIZE, nbytes);
                bytes_to_write =
                    ((((nb + sb->s_blocksize - 1)) >> sb->s_blocksize_bits))
                    << sb->s_blocksize_bits;

                if (!(mp = get_metapage(ip, blkno + i, bytes_to_write, 1))) {
                        rc = -EIO;
                        goto failed;
                }

                memcpy(mp->data, cp, nb);

                /*
                 * We really need a way to propagate errors for
                 * forced writes like this one.  --hch
                 *
                 * (__write_metapage => release_metapage => flush_metapage)
                 */
#ifdef _JFS_FIXME
                if ((rc = flush_metapage(mp))) {
                        /*
                         * the write failed -- this means that the buffer
                         * is still assigned and the blocks are not being
                         * used.  this seems like the best error recovery
                         * we can get ...
                         */
                        goto failed;
                }
#else
                flush_metapage(mp);
#endif

                cp += PSIZE;
                nbytes -= nb;
        }

        ea->flag = DXD_EXTENT;
        DXDsize(ea, le32_to_cpu(ealist->size));
        DXDlength(ea, nblocks);
        DXDaddress(ea, blkno);

        /* Free up INLINE area */
        if (ji->ea.flag & DXD_INLINE)
                ji->mode2 |= INLINEEA;

        return 0;

      failed:
        /* Rollback quota allocation. */
        vfs_dq_free_block(ip, nblocks);

        dbFree(ip, blkno, nblocks);
        return rc;
}

/*
 * NAME: ea_read_inline
 *
 * FUNCTION: Read an inlined EA into user's buffer
 *
 * PARAMETERS:
 *      ip      - Inode pointer
 *      ealist  - Pointer to buffer to fill in with EA
 *
 * RETURNS: 0
 */
static int ea_read_inline(struct inode *ip, struct jfs_ea_list *ealist)
{
        struct jfs_inode_info *ji = JFS_IP(ip);
        int ea_size = sizeDXD(&ji->ea);

        if (ea_size == 0) {
                ealist->size = 0;
                return 0;
        }

        /* Sanity Check */
        if ((sizeDXD(&ji->ea) > sizeof (ji->i_inline_ea)))
                return -EIO;
        if (le32_to_cpu(((struct jfs_ea_list *) &ji->i_inline_ea)->size)
            != ea_size)
                return -EIO;

        memcpy(ealist, ji->i_inline_ea, ea_size);
        return 0;
}

/*
 * NAME: ea_read
 *
 * FUNCTION: copy EA data into user's buffer
 *
 * PARAMETERS:
 *      ip      - Inode pointer
 *      ealist  - Pointer to buffer to fill in with EA
 *
 * NOTES:  If EA is inline calls ea_read_inline() to copy EA.
 *
 * RETURNS: 0 for success; other indicates failure
 */
static int ea_read(struct inode *ip, struct jfs_ea_list *ealist)
{
        struct super_block *sb = ip->i_sb;
        struct jfs_inode_info *ji = JFS_IP(ip);
        struct jfs_sb_info *sbi = JFS_SBI(sb);
        int nblocks;
        s64 blkno;
        char *cp = (char *) ealist;
        int i;
        int nbytes, nb;
        s32 bytes_to_read;
        struct metapage *mp;

        /* quick check for in-line EA */
        if (ji->ea.flag & DXD_INLINE)
                return ea_read_inline(ip, ealist);

        nbytes = sizeDXD(&ji->ea);
        if (!nbytes) {
                jfs_error(sb, "ea_read: nbytes is 0");
                return -EIO;
        }

        /*
         * Figure out how many blocks were allocated when this EA list was
         * originally written to disk.
         */
        nblocks = lengthDXD(&ji->ea) << sbi->l2nbperpage;
        blkno = addressDXD(&ji->ea) << sbi->l2nbperpage;

        /*
         * I have found the disk blocks which were originally used to store
         * the FEALIST.  now i loop over each contiguous block copying the
         * data into the buffer.
         */
        for (i = 0; i < nblocks; i += sbi->nbperpage) {
                /*
                 * Determine how many bytes for this request, and round up to
                 * the nearest aggregate block size
                 */
                nb = min(PSIZE, nbytes);
                bytes_to_read =
                    ((((nb + sb->s_blocksize - 1)) >> sb->s_blocksize_bits))
                    << sb->s_blocksize_bits;

                if (!(mp = read_metapage(ip, blkno + i, bytes_to_read, 1)))
                        return -EIO;

                memcpy(cp, mp->data, nb);
                release_metapage(mp);

                cp += PSIZE;
                nbytes -= nb;
        }

        return 0;
}

/*
 * NAME: ea_get
 *
 * FUNCTION: Returns buffer containing existing extended attributes.
 *           The size of the buffer will be the larger of the existing
 *           attributes size, or min_size.
 *
 *           The buffer, which may be inlined in the inode or in the
 *           page cache must be release by calling ea_release or ea_put
 *
 * PARAMETERS:
 *      inode   - Inode pointer
 *      ea_buf  - Structure to be populated with ealist and its metadata
 *      min_size- minimum size of buffer to be returned
 *
 * RETURNS: 0 for success; Other indicates failure
 */
static int ea_get(struct inode *inode, struct ea_buffer *ea_buf, int min_size)
{
        struct jfs_inode_info *ji = JFS_IP(inode);
        struct super_block *sb = inode->i_sb;
        int size;
        int ea_size = sizeDXD(&ji->ea);
        int blocks_needed, current_blocks;
        s64 blkno;
        int rc;
        int quota_allocation = 0;

        /* When fsck.jfs clears a bad ea, it doesn't clear the size */
        if (ji->ea.flag == 0)
                ea_size = 0;

        if (ea_size == 0) {
                if (min_size == 0) {
                        ea_buf->flag = 0;
                        ea_buf->max_size = 0;
                        ea_buf->xattr = NULL;
                        return 0;
                }
                if ((min_size <= sizeof (ji->i_inline_ea)) &&
                    (ji->mode2 & INLINEEA)) {
                        ea_buf->flag = EA_INLINE | EA_NEW;
                        ea_buf->max_size = sizeof (ji->i_inline_ea);
                        ea_buf->xattr = (struct jfs_ea_list *) ji->i_inline_ea;
                        DXDlength(&ea_buf->new_ea, 0);
                        DXDaddress(&ea_buf->new_ea, 0);
                        ea_buf->new_ea.flag = DXD_INLINE;
                        DXDsize(&ea_buf->new_ea, min_size);
                        return 0;
                }
                current_blocks = 0;
        } else if (ji->ea.flag & DXD_INLINE) {
                if (min_size <= sizeof (ji->i_inline_ea)) {
                        ea_buf->flag = EA_INLINE;
                        ea_buf->max_size = sizeof (ji->i_inline_ea);
                        ea_buf->xattr = (struct jfs_ea_list *) ji->i_inline_ea;
                        goto size_check;
                }
                current_blocks = 0;
        } else {
                if (!(ji->ea.flag & DXD_EXTENT)) {
                        jfs_error(sb, "ea_get: invalid ea.flag)");
                        return -EIO;
                }
                current_blocks = (ea_size + sb->s_blocksize - 1) >>
                    sb->s_blocksize_bits;
        }
        size = max(min_size, ea_size);

        if (size > PSIZE) {
                /*
                 * To keep the rest of the code simple.  Allocate a
                 * contiguous buffer to work with
                 */
                ea_buf->xattr = kmalloc(size, GFP_KERNEL);
                if (ea_buf->xattr == NULL)
                        return -ENOMEM;

                ea_buf->flag = EA_MALLOC;
                ea_buf->max_size = (size + sb->s_blocksize - 1) &
                    ~(sb->s_blocksize - 1);

                if (ea_size == 0)
                        return 0;

                if ((rc = ea_read(inode, ea_buf->xattr))) {
                        kfree(ea_buf->xattr);
                        ea_buf->xattr = NULL;
                        return rc;
                }
                goto size_check;
        }
        blocks_needed = (min_size + sb->s_blocksize - 1) >>
            sb->s_blocksize_bits;

        if (blocks_needed > current_blocks) {
                /* Allocate new blocks to quota. */
                if (vfs_dq_alloc_block(inode, blocks_needed))
                        return -EDQUOT;

                quota_allocation = blocks_needed;

                rc = dbAlloc(inode, INOHINT(inode), (s64) blocks_needed,
                             &blkno);
                if (rc)
                        goto clean_up;

                DXDlength(&ea_buf->new_ea, blocks_needed);
                DXDaddress(&ea_buf->new_ea, blkno);
                ea_buf->new_ea.flag = DXD_EXTENT;
                DXDsize(&ea_buf->new_ea, min_size);

                ea_buf->flag = EA_EXTENT | EA_NEW;

                ea_buf->mp = get_metapage(inode, blkno,
                                          blocks_needed << sb->s_blocksize_bits,
                                          1);
                if (ea_buf->mp == NULL) {
                        dbFree(inode, blkno, (s64) blocks_needed);
                        rc = -EIO;
                        goto clean_up;
                }
                ea_buf->xattr = ea_buf->mp->data;
                ea_buf->max_size = (min_size + sb->s_blocksize - 1) &
                    ~(sb->s_blocksize - 1);
                if (ea_size == 0)
                        return 0;
                if ((rc = ea_read(inode, ea_buf->xattr))) {
                        discard_metapage(ea_buf->mp);
                        dbFree(inode, blkno, (s64) blocks_needed);
                        goto clean_up;
                }
                goto size_check;
        }
        ea_buf->flag = EA_EXTENT;
        ea_buf->mp = read_metapage(inode, addressDXD(&ji->ea),
                                   lengthDXD(&ji->ea) << sb->s_blocksize_bits,
                                   1);
        if (ea_buf->mp == NULL) {
                rc = -EIO;
                goto clean_up;
        }
        ea_buf->xattr = ea_buf->mp->data;
        ea_buf->max_size = (ea_size + sb->s_blocksize - 1) &
            ~(sb->s_blocksize - 1);

      size_check:
        if (EALIST_SIZE(ea_buf->xattr) != ea_size) {
                printk(KERN_ERR "ea_get: invalid extended attribute\n");
                print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1,
                                     ea_buf->xattr, ea_size, 1);
                ea_release(inode, ea_buf);
                rc = -EIO;
                goto clean_up;
        }

        return ea_size;

      clean_up:
        /* Rollback quota allocation */
        if (quota_allocation)
                vfs_dq_free_block(inode, quota_allocation);

        return (rc);
}

static void ea_release(struct inode *inode, struct ea_buffer *ea_buf)
{
        if (ea_buf->flag & EA_MALLOC)
                kfree(ea_buf->xattr);
        else if (ea_buf->flag & EA_EXTENT) {
                assert(ea_buf->mp);
                release_metapage(ea_buf->mp);

                if (ea_buf->flag & EA_NEW)
                        dbFree(inode, addressDXD(&ea_buf->new_ea),
                               lengthDXD(&ea_buf->new_ea));
        }
}

static int ea_put(tid_t tid, struct inode *inode, struct ea_buffer *ea_buf,
                  int new_size)
{
        struct jfs_inode_info *ji = JFS_IP(inode);
        unsigned long old_blocks, new_blocks;
        int rc = 0;

        if (new_size == 0) {
                ea_release(inode, ea_buf);
                ea_buf = NULL;
        } else if (ea_buf->flag & EA_INLINE) {
                assert(new_size <= sizeof (ji->i_inline_ea));
                ji->mode2 &= ~INLINEEA;
                ea_buf->new_ea.flag = DXD_INLINE;
                DXDsize(&ea_buf->new_ea, new_size);
                DXDaddress(&ea_buf->new_ea, 0);
                DXDlength(&ea_buf->new_ea, 0);
        } else if (ea_buf->flag & EA_MALLOC) {
                rc = ea_write(inode, ea_buf->xattr, new_size, &ea_buf->new_ea);
                kfree(ea_buf->xattr);
        } else if (ea_buf->flag & EA_NEW) {
                /* We have already allocated a new dxd */
                flush_metapage(ea_buf->mp);
        } else {
                /* ->xattr must point to original ea's metapage */
                rc = ea_write(inode, ea_buf->xattr, new_size, &ea_buf->new_ea);
                discard_metapage(ea_buf->mp);
        }
        if (rc)
                return rc;

        old_blocks = new_blocks = 0;

        if (ji->ea.flag & DXD_EXTENT) {
                invalidate_dxd_metapages(inode, ji->ea);
                old_blocks = lengthDXD(&ji->ea);
        }

        if (ea_buf) {
                txEA(tid, inode, &ji->ea, &ea_buf->new_ea);
                if (ea_buf->new_ea.flag & DXD_EXTENT) {
                        new_blocks = lengthDXD(&ea_buf->new_ea);
                        if (ji->ea.flag & DXD_INLINE)
                                ji->mode2 |= INLINEEA;
                }
                ji->ea = ea_buf->new_ea;
        } else {
                txEA(tid, inode, &ji->ea, NULL);
                if (ji->ea.flag & DXD_INLINE)
                        ji->mode2 |= INLINEEA;
                ji->ea.flag = 0;
                ji->ea.size = 0;
        }

        /* If old blocks exist, they must be removed from quota allocation. */
        if (old_blocks)
                vfs_dq_free_block(inode, old_blocks);

        inode->i_ctime = CURRENT_TIME;

        return 0;
}

/*
 * can_set_system_xattr
 *
 * This code is specific to the system.* namespace.  It contains policy
 * which doesn't belong in the main xattr codepath.
 */
static int can_set_system_xattr(struct inode *inode, const char *name,
                                const void *value, size_t value_len)
{
#ifdef CONFIG_JFS_POSIX_ACL
        struct posix_acl *acl;
        int rc;

        if (!is_owner_or_cap(inode))
                return -EPERM;

        /*
         * POSIX_ACL_XATTR_ACCESS is tied to i_mode
         */
        if (strcmp(name, POSIX_ACL_XATTR_ACCESS) == 0) {
                acl = posix_acl_from_xattr(value, value_len);
                if (IS_ERR(acl)) {
                        rc = PTR_ERR(acl);
                        printk(KERN_ERR "posix_acl_from_xattr returned %d\n",
                               rc);
                        return rc;
                }
                if (acl) {
                        mode_t mode = inode->i_mode;
                        rc = posix_acl_equiv_mode(acl, &mode);
                        posix_acl_release(acl);
                        if (rc < 0) {
                                printk(KERN_ERR
                                       "posix_acl_equiv_mode returned %d\n",
                                       rc);
                                return rc;
                        }
                        inode->i_mode = mode;
                        mark_inode_dirty(inode);
                }
                /*
                 * We're changing the ACL.  Get rid of the cached one
                 */
                forget_cached_acl(inode, ACL_TYPE_ACCESS);

                return 0;
        } else if (strcmp(name, POSIX_ACL_XATTR_DEFAULT) == 0) {
                acl = posix_acl_from_xattr(value, value_len);
                if (IS_ERR(acl)) {
                        rc = PTR_ERR(acl);
                        printk(KERN_ERR "posix_acl_from_xattr returned %d\n",
                               rc);
                        return rc;
                }
                posix_acl_release(acl);

                /*
                 * We're changing the default ACL.  Get rid of the cached one
                 */
                forget_cached_acl(inode, ACL_TYPE_DEFAULT);

                return 0;
        }
#endif                  /* CONFIG_JFS_POSIX_ACL */
        return -EOPNOTSUPP;
}

/*
 * Most of the permission checking is done by xattr_permission in the vfs.
 * The local file system is responsible for handling the system.* namespace.
 * We also need to verify that this is a namespace that we recognize.
 */
static int can_set_xattr(struct inode *inode, const char *name,
                         const void *value, size_t value_len)
{
        if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
                return can_set_system_xattr(inode, name, value, value_len);

        if (!strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN)) {
                /*
                 * This makes sure that we aren't trying to set an
                 * attribute in a different namespace by prefixing it
                 * with "os2."
                 */
                if (is_known_namespace(name + XATTR_OS2_PREFIX_LEN))
                                return -EOPNOTSUPP;
                return 0;
        }

        /*
         * Don't allow setting an attribute in an unknown namespace.
         */
        if (strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) &&
            strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) &&
            strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
                return -EOPNOTSUPP;

        return 0;
}

int __jfs_setxattr(tid_t tid, struct inode *inode, const char *name,
                   const void *value, size_t value_len, int flags)
{
        struct jfs_ea_list *ealist;
        struct jfs_ea *ea, *old_ea = NULL, *next_ea = NULL;
        struct ea_buffer ea_buf;
        int old_ea_size = 0;
        int xattr_size;
        int new_size;
        int namelen = strlen(name);
        char *os2name = NULL;
        int found = 0;
        int rc;
        int length;

        if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
                os2name = kmalloc(namelen - XATTR_OS2_PREFIX_LEN + 1,
                                  GFP_KERNEL);
                if (!os2name)
                        return -ENOMEM;
                strcpy(os2name, name + XATTR_OS2_PREFIX_LEN);
                name = os2name;
                namelen -= XATTR_OS2_PREFIX_LEN;
        }

        down_write(&JFS_IP(inode)->xattr_sem);

        xattr_size = ea_get(inode, &ea_buf, 0);
        if (xattr_size < 0) {
                rc = xattr_size;
                goto out;
        }

      again:
        ealist = (struct jfs_ea_list *) ea_buf.xattr;
        new_size = sizeof (struct jfs_ea_list);

        if (xattr_size) {
                for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist);
                     ea = NEXT_EA(ea)) {
                        if ((namelen == ea->namelen) &&
                            (memcmp(name, ea->name, namelen) == 0)) {
                                found = 1;
                                if (flags & XATTR_CREATE) {
                                        rc = -EEXIST;
                                        goto release;
                                }
                                old_ea = ea;
                                old_ea_size = EA_SIZE(ea);
                                next_ea = NEXT_EA(ea);
                        } else
                                new_size += EA_SIZE(ea);
                }
        }

        if (!found) {
                if (flags & XATTR_REPLACE) {
                        rc = -ENODATA;
                        goto release;
                }
                if (value == NULL) {
                        rc = 0;
                        goto release;
                }
        }
        if (value)
                new_size += sizeof (struct jfs_ea) + namelen + 1 + value_len;

        if (new_size > ea_buf.max_size) {
                /*
                 * We need to allocate more space for merged ea list.
                 * We should only have loop to again: once.
                 */
                ea_release(inode, &ea_buf);
                xattr_size = ea_get(inode, &ea_buf, new_size);
                if (xattr_size < 0) {
                        rc = xattr_size;
                        goto out;
                }
                goto again;
        }

        /* Remove old ea of the same name */
        if (found) {
                /* number of bytes following target EA */
                length = (char *) END_EALIST(ealist) - (char *) next_ea;
                if (length > 0)
                        memmove(old_ea, next_ea, length);
                xattr_size -= old_ea_size;
        }

        /* Add new entry to the end */
        if (value) {
                if (xattr_size == 0)
                        /* Completely new ea list */
                        xattr_size = sizeof (struct jfs_ea_list);

                ea = (struct jfs_ea *) ((char *) ealist + xattr_size);
                ea->flag = 0;
                ea->namelen = namelen;
                ea->valuelen = (cpu_to_le16(value_len));
                memcpy(ea->name, name, namelen);
                ea->name[namelen] = 0;
                if (value_len)
                        memcpy(&ea->name[namelen + 1], value, value_len);
                xattr_size += EA_SIZE(ea);
        }

        /* DEBUG - If we did this right, these number match */
        if (xattr_size != new_size) {
                printk(KERN_ERR
                       "jfs_xsetattr: xattr_size = %d, new_size = %d\n",
                       xattr_size, new_size);

                rc = -EINVAL;
                goto release;
        }

        /*
         * If we're left with an empty list, there's no ea
         */
        if (new_size == sizeof (struct jfs_ea_list))
                new_size = 0;

        ealist->size = cpu_to_le32(new_size);

        rc = ea_put(tid, inode, &ea_buf, new_size);

        goto out;
      release:
        ea_release(inode, &ea_buf);
      out:
        up_write(&JFS_IP(inode)->xattr_sem);

        kfree(os2name);

        return rc;
}

int jfs_setxattr(struct dentry *dentry, const char *name, const void *value,
                 size_t value_len, int flags)
{
        struct inode *inode = dentry->d_inode;
        struct jfs_inode_info *ji = JFS_IP(inode);
        int rc;
        tid_t tid;

        if ((rc = can_set_xattr(inode, name, value, value_len)))
                return rc;

        if (value == NULL) {    /* empty EA, do not remove */
                value = "";
                value_len = 0;
        }

        tid = txBegin(inode->i_sb, 0);
        mutex_lock(&ji->commit_mutex);
        rc = __jfs_setxattr(tid, dentry->d_inode, name, value, value_len,
                            flags);
        if (!rc)
                rc = txCommit(tid, 1, &inode, 0);
        txEnd(tid);
        mutex_unlock(&ji->commit_mutex);

        return rc;
}

ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
                       size_t buf_size)
{
        struct jfs_ea_list *ealist;
        struct jfs_ea *ea;
        struct ea_buffer ea_buf;
        int xattr_size;
        ssize_t size;
        int namelen = strlen(name);
        char *value;

        down_read(&JFS_IP(inode)->xattr_sem);

        xattr_size = ea_get(inode, &ea_buf, 0);

        if (xattr_size < 0) {
                size = xattr_size;
                goto out;
        }

        if (xattr_size == 0)
                goto not_found;

        ealist = (struct jfs_ea_list *) ea_buf.xattr;

        /* Find the named attribute */
        for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea))
                if ((namelen == ea->namelen) &&
                    memcmp(name, ea->name, namelen) == 0) {
                        /* Found it */
                        size = le16_to_cpu(ea->valuelen);
                        if (!data)
                                goto release;
                        else if (size > buf_size) {
                                size = -ERANGE;
                                goto release;
                        }
                        value = ((char *) &ea->name) + ea->namelen + 1;
                        memcpy(data, value, size);
                        goto release;
                }
      not_found:
        size = -ENODATA;
      release:
        ea_release(inode, &ea_buf);
      out:
        up_read(&JFS_IP(inode)->xattr_sem);

        return size;
}

ssize_t jfs_getxattr(struct dentry *dentry, const char *name, void *data,
                     size_t buf_size)
{
        int err;

        if (strncmp(name, XATTR_OS2_PREFIX, XATTR_OS2_PREFIX_LEN) == 0) {
                /*
                 * skip past "os2." prefix
                 */
                name += XATTR_OS2_PREFIX_LEN;
                /*
                 * Don't allow retrieving properly prefixed attributes
                 * by prepending them with "os2."
                 */
                if (is_known_namespace(name))
                        return -EOPNOTSUPP;
        }

        err = __jfs_getxattr(dentry->d_inode, name, data, buf_size);

        return err;
}

/*
 * No special permissions are needed to list attributes except for trusted.*
 */
static inline int can_list(struct jfs_ea *ea)
{
        return (strncmp(ea->name, XATTR_TRUSTED_PREFIX,
                            XATTR_TRUSTED_PREFIX_LEN) ||
                capable(CAP_SYS_ADMIN));
}

ssize_t jfs_listxattr(struct dentry * dentry, char *data, size_t buf_size)
{
        struct inode *inode = dentry->d_inode;
        char *buffer;
        ssize_t size = 0;
        int xattr_size;
        struct jfs_ea_list *ealist;
        struct jfs_ea *ea;
        struct ea_buffer ea_buf;

        down_read(&JFS_IP(inode)->xattr_sem);

        xattr_size = ea_get(inode, &ea_buf, 0);
        if (xattr_size < 0) {
                size = xattr_size;
                goto out;
        }

        if (xattr_size == 0)
                goto release;

        ealist = (struct jfs_ea_list *) ea_buf.xattr;

        /* compute required size of list */
        for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
                if (can_list(ea))
                        size += name_size(ea) + 1;
        }

        if (!data)
                goto release;

        if (size > buf_size) {
                size = -ERANGE;
                goto release;
        }

        /* Copy attribute names to buffer */
        buffer = data;
        for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
                if (can_list(ea)) {
                        int namelen = copy_name(buffer, ea);
                        buffer += namelen + 1;
                }
        }

      release:
        ea_release(inode, &ea_buf);
      out:
        up_read(&JFS_IP(inode)->xattr_sem);
        return size;
}

int jfs_removexattr(struct dentry *dentry, const char *name)
{
        struct inode *inode = dentry->d_inode;
        struct jfs_inode_info *ji = JFS_IP(inode);
        int rc;
        tid_t tid;

        if ((rc = can_set_xattr(inode, name, NULL, 0)))
                return rc;

        tid = txBegin(inode->i_sb, 0);
        mutex_lock(&ji->commit_mutex);
        rc = __jfs_setxattr(tid, dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
        if (!rc)
                rc = txCommit(tid, 1, &inode, 0);
        txEnd(tid);
        mutex_unlock(&ji->commit_mutex);

        return rc;
}

#ifdef CONFIG_JFS_SECURITY
int jfs_init_security(tid_t tid, struct inode *inode, struct inode *dir)
{
        int rc;
        size_t len;
        void *value;
        char *suffix;
        char *name;

        rc = security_inode_init_security(inode, dir, &suffix, &value, &len);
        if (rc) {
                if (rc == -EOPNOTSUPP)
                        return 0;
                return rc;
        }
        name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 1 + strlen(suffix),
                       GFP_NOFS);
        if (!name) {
                rc = -ENOMEM;
                goto kmalloc_failed;
        }
        strcpy(name, XATTR_SECURITY_PREFIX);
        strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);

        rc = __jfs_setxattr(tid, inode, name, value, len, 0);

        kfree(name);
kmalloc_failed:
        kfree(suffix);
        kfree(value);

        return rc;
}
#endif