xattr.c

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#include <linux/ceph/ceph_debug.h>

#include "super.h"
#include "mds_client.h"

#include <linux/ceph/decode.h>

#include <linux/xattr.h>
#include <linux/slab.h>

#define XATTR_CEPH_PREFIX "ceph."
#define XATTR_CEPH_PREFIX_LEN (sizeof (XATTR_CEPH_PREFIX) - 1)

static bool ceph_is_valid_xattr(const char *name)
{
    return !strncmp(name, XATTR_CEPH_PREFIX, XATTR_CEPH_PREFIX_LEN) ||
           !strncmp(name, XATTR_SECURITY_PREFIX,
            XATTR_SECURITY_PREFIX_LEN) ||
           !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
           !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
}

/*
 * These define virtual xattrs exposing the recursive directory
 * statistics and layout metadata.
 */
struct ceph_vxattr {
    char *name;
    size_t name_size;   /* strlen(name) + 1 (for '\0') */
    size_t (*getxattr_cb)(struct ceph_inode_info *ci, char *val,
                  size_t size);
    bool readonly;
};

/* directories */

static size_t ceph_vxattrcb_dir_entries(struct ceph_inode_info *ci, char *val,
                    size_t size)
{
    return snprintf(val, size, "%lld", ci->i_files + ci->i_subdirs);
}

static size_t ceph_vxattrcb_dir_files(struct ceph_inode_info *ci, char *val,
                      size_t size)
{
    return snprintf(val, size, "%lld", ci->i_files);
}

static size_t ceph_vxattrcb_dir_subdirs(struct ceph_inode_info *ci, char *val,
                    size_t size)
{
    return snprintf(val, size, "%lld", ci->i_subdirs);
}

static size_t ceph_vxattrcb_dir_rentries(struct ceph_inode_info *ci, char *val,
                     size_t size)
{
    return snprintf(val, size, "%lld", ci->i_rfiles + ci->i_rsubdirs);
}

static size_t ceph_vxattrcb_dir_rfiles(struct ceph_inode_info *ci, char *val,
                       size_t size)
{
    return snprintf(val, size, "%lld", ci->i_rfiles);
}

static size_t ceph_vxattrcb_dir_rsubdirs(struct ceph_inode_info *ci, char *val,
                     size_t size)
{
    return snprintf(val, size, "%lld", ci->i_rsubdirs);
}

static size_t ceph_vxattrcb_dir_rbytes(struct ceph_inode_info *ci, char *val,
                       size_t size)
{
    return snprintf(val, size, "%lld", ci->i_rbytes);
}

static size_t ceph_vxattrcb_dir_rctime(struct ceph_inode_info *ci, char *val,
                       size_t size)
{
    return snprintf(val, size, "%ld.09%ld", (long)ci->i_rctime.tv_sec,
            (long)ci->i_rctime.tv_nsec);
}

#define CEPH_XATTR_NAME(_type, _name)   XATTR_CEPH_PREFIX #_type "." #_name

#define XATTR_NAME_CEPH(_type, _name) \
        { \
            .name = CEPH_XATTR_NAME(_type, _name), \
            .name_size = sizeof (CEPH_XATTR_NAME(_type, _name)), \
            .getxattr_cb = ceph_vxattrcb_ ## _type ## _ ## _name, \
            .readonly = true, \
        }

static struct ceph_vxattr ceph_dir_vxattrs[] = {
    XATTR_NAME_CEPH(dir, entries),
    XATTR_NAME_CEPH(dir, files),
    XATTR_NAME_CEPH(dir, subdirs),
    XATTR_NAME_CEPH(dir, rentries),
    XATTR_NAME_CEPH(dir, rfiles),
    XATTR_NAME_CEPH(dir, rsubdirs),
    XATTR_NAME_CEPH(dir, rbytes),
    XATTR_NAME_CEPH(dir, rctime),
    { 0 }   /* Required table terminator */
};
static size_t ceph_dir_vxattrs_name_size;   /* total size of all names */

/* files */

static size_t ceph_vxattrcb_file_layout(struct ceph_inode_info *ci, char *val,
                   size_t size)
{
    int ret;

    ret = snprintf(val, size,
        "chunk_bytes=%lld\nstripe_count=%lld\nobject_size=%lld\n",
        (unsigned long long)ceph_file_layout_su(ci->i_layout),
        (unsigned long long)ceph_file_layout_stripe_count(ci->i_layout),
        (unsigned long long)ceph_file_layout_object_size(ci->i_layout));
    return ret;
}

static struct ceph_vxattr ceph_file_vxattrs[] = {
    XATTR_NAME_CEPH(file, layout),
    /* The following extended attribute name is deprecated */
    {
        .name = XATTR_CEPH_PREFIX "layout",
        .name_size = sizeof (XATTR_CEPH_PREFIX "layout"),
        .getxattr_cb = ceph_vxattrcb_file_layout,
        .readonly = true,
    },
    { 0 }   /* Required table terminator */
};
static size_t ceph_file_vxattrs_name_size;  /* total size of all names */

static struct ceph_vxattr *ceph_inode_vxattrs(struct inode *inode)
{
    if (S_ISDIR(inode->i_mode))
        return ceph_dir_vxattrs;
    else if (S_ISREG(inode->i_mode))
        return ceph_file_vxattrs;
    return NULL;
}

static size_t ceph_vxattrs_name_size(struct ceph_vxattr *vxattrs)
{
    if (vxattrs == ceph_dir_vxattrs)
        return ceph_dir_vxattrs_name_size;
    if (vxattrs == ceph_file_vxattrs)
        return ceph_file_vxattrs_name_size;
    BUG();

    return 0;
}

/*
 * Compute the aggregate size (including terminating '\0') of all
 * virtual extended attribute names in the given vxattr table.
 */
static size_t __init vxattrs_name_size(struct ceph_vxattr *vxattrs)
{
    struct ceph_vxattr *vxattr;
    size_t size = 0;

    for (vxattr = vxattrs; vxattr->name; vxattr++)
        size += vxattr->name_size;

    return size;
}

/* Routines called at initialization and exit time */

void __init ceph_xattr_init(void)
{
    ceph_dir_vxattrs_name_size = vxattrs_name_size(ceph_dir_vxattrs);
    ceph_file_vxattrs_name_size = vxattrs_name_size(ceph_file_vxattrs);
}

void ceph_xattr_exit(void)
{
    ceph_dir_vxattrs_name_size = 0;
    ceph_file_vxattrs_name_size = 0;
}

static struct ceph_vxattr *ceph_match_vxattr(struct inode *inode,
                        const char *name)
{
    struct ceph_vxattr *vxattr = ceph_inode_vxattrs(inode);

    if (vxattr) {
        while (vxattr->name) {
            if (!strcmp(vxattr->name, name))
                return vxattr;
            vxattr++;
        }
    }

    return NULL;
}

static int __set_xattr(struct ceph_inode_info *ci,
               const char *name, int name_len,
               const char *val, int val_len,
               int dirty,
               int should_free_name, int should_free_val,
               struct ceph_inode_xattr **newxattr)
{
    struct rb_node **p;
    struct rb_node *parent = NULL;
    struct ceph_inode_xattr *xattr = NULL;
    int c;
    int new = 0;

    p = &ci->i_xattrs.index.rb_node;
    while (*p) {
        parent = *p;
        xattr = rb_entry(parent, struct ceph_inode_xattr, node);
        c = strncmp(name, xattr->name, min(name_len, xattr->name_len));
        if (c < 0)
            p = &(*p)->rb_left;
        else if (c > 0)
            p = &(*p)->rb_right;
        else {
            if (name_len == xattr->name_len)
                break;
            else if (name_len < xattr->name_len)
                p = &(*p)->rb_left;
            else
                p = &(*p)->rb_right;
        }
        xattr = NULL;
    }

    if (!xattr) {
        new = 1;
        xattr = *newxattr;
        xattr->name = name;
        xattr->name_len = name_len;
        xattr->should_free_name = should_free_name;

        ci->i_xattrs.count++;
        dout("__set_xattr count=%d\n", ci->i_xattrs.count);
    } else {
        kfree(*newxattr);
        *newxattr = NULL;
        if (xattr->should_free_val)
            kfree((void *)xattr->val);

        if (should_free_name) {
            kfree((void *)name);
            name = xattr->name;
        }
        ci->i_xattrs.names_size -= xattr->name_len;
        ci->i_xattrs.vals_size -= xattr->val_len;
    }
    ci->i_xattrs.names_size += name_len;
    ci->i_xattrs.vals_size += val_len;
    if (val)
        xattr->val = val;
    else
        xattr->val = "";

    xattr->val_len = val_len;
    xattr->dirty = dirty;
    xattr->should_free_val = (val && should_free_val);

    if (new) {
        rb_link_node(&xattr->node, parent, p);
        rb_insert_color(&xattr->node, &ci->i_xattrs.index);
        dout("__set_xattr_val p=%p\n", p);
    }

    dout("__set_xattr_val added %llx.%llx xattr %p %s=%.*s\n",
         ceph_vinop(&ci->vfs_inode), xattr, name, val_len, val);

    return 0;
}

static struct ceph_inode_xattr *__get_xattr(struct ceph_inode_info *ci,
               const char *name)
{
    struct rb_node **p;
    struct rb_node *parent = NULL;
    struct ceph_inode_xattr *xattr = NULL;
    int name_len = strlen(name);
    int c;

    p = &ci->i_xattrs.index.rb_node;
    while (*p) {
        parent = *p;
        xattr = rb_entry(parent, struct ceph_inode_xattr, node);
        c = strncmp(name, xattr->name, xattr->name_len);
        if (c == 0 && name_len > xattr->name_len)
            c = 1;
        if (c < 0)
            p = &(*p)->rb_left;
        else if (c > 0)
            p = &(*p)->rb_right;
        else {
            dout("__get_xattr %s: found %.*s\n", name,
                 xattr->val_len, xattr->val);
            return xattr;
        }
    }

    dout("__get_xattr %s: not found\n", name);

    return NULL;
}

static void __free_xattr(struct ceph_inode_xattr *xattr)
{
    BUG_ON(!xattr);

    if (xattr->should_free_name)
        kfree((void *)xattr->name);
    if (xattr->should_free_val)
        kfree((void *)xattr->val);

    kfree(xattr);
}

static int __remove_xattr(struct ceph_inode_info *ci,
              struct ceph_inode_xattr *xattr)
{
    if (!xattr)
        return -EOPNOTSUPP;

    rb_erase(&xattr->node, &ci->i_xattrs.index);

    if (xattr->should_free_name)
        kfree((void *)xattr->name);
    if (xattr->should_free_val)
        kfree((void *)xattr->val);

    ci->i_xattrs.names_size -= xattr->name_len;
    ci->i_xattrs.vals_size -= xattr->val_len;
    ci->i_xattrs.count--;
    kfree(xattr);

    return 0;
}

static int __remove_xattr_by_name(struct ceph_inode_info *ci,
               const char *name)
{
    struct rb_node **p;
    struct ceph_inode_xattr *xattr;
    int err;

    p = &ci->i_xattrs.index.rb_node;
    xattr = __get_xattr(ci, name);
    err = __remove_xattr(ci, xattr);
    return err;
}

static char *__copy_xattr_names(struct ceph_inode_info *ci,
                char *dest)
{
    struct rb_node *p;
    struct ceph_inode_xattr *xattr = NULL;

    p = rb_first(&ci->i_xattrs.index);
    dout("__copy_xattr_names count=%d\n", ci->i_xattrs.count);

    while (p) {
        xattr = rb_entry(p, struct ceph_inode_xattr, node);
        memcpy(dest, xattr->name, xattr->name_len);
        dest[xattr->name_len] = '\0';

        dout("dest=%s %p (%s) (%d/%d)\n", dest, xattr, xattr->name,
             xattr->name_len, ci->i_xattrs.names_size);

        dest += xattr->name_len + 1;
        p = rb_next(p);
    }

    return dest;
}

void __ceph_destroy_xattrs(struct ceph_inode_info *ci)
{
    struct rb_node *p, *tmp;
    struct ceph_inode_xattr *xattr = NULL;

    p = rb_first(&ci->i_xattrs.index);

    dout("__ceph_destroy_xattrs p=%p\n", p);

    while (p) {
        xattr = rb_entry(p, struct ceph_inode_xattr, node);
        tmp = p;
        p = rb_next(tmp);
        dout("__ceph_destroy_xattrs next p=%p (%.*s)\n", p,
             xattr->name_len, xattr->name);
        rb_erase(tmp, &ci->i_xattrs.index);

        __free_xattr(xattr);
    }

    ci->i_xattrs.names_size = 0;
    ci->i_xattrs.vals_size = 0;
    ci->i_xattrs.index_version = 0;
    ci->i_xattrs.count = 0;
    ci->i_xattrs.index = RB_ROOT;
}

static int __build_xattrs(struct inode *inode)
    __releases(ci->i_ceph_lock)
    __acquires(ci->i_ceph_lock)
{
    u32 namelen;
    u32 numattr = 0;
    void *p, *end;
    u32 len;
    const char *name, *val;
    struct ceph_inode_info *ci = ceph_inode(inode);
    int xattr_version;
    struct ceph_inode_xattr **xattrs = NULL;
    int err = 0;
    int i;

    dout("__build_xattrs() len=%d\n",
         ci->i_xattrs.blob ? (int)ci->i_xattrs.blob->vec.iov_len : 0);

    if (ci->i_xattrs.index_version >= ci->i_xattrs.version)
        return 0; /* already built */

    __ceph_destroy_xattrs(ci);

start:
    /* updated internal xattr rb tree */
    if (ci->i_xattrs.blob && ci->i_xattrs.blob->vec.iov_len > 4) {
        p = ci->i_xattrs.blob->vec.iov_base;
        end = p + ci->i_xattrs.blob->vec.iov_len;
        ceph_decode_32_safe(&p, end, numattr, bad);
        xattr_version = ci->i_xattrs.version;
        spin_unlock(&ci->i_ceph_lock);

        xattrs = kcalloc(numattr, sizeof(struct ceph_xattr *),
                 GFP_NOFS);
        err = -ENOMEM;
        if (!xattrs)
            goto bad_lock;
        memset(xattrs, 0, numattr*sizeof(struct ceph_xattr *));
        for (i = 0; i < numattr; i++) {
            xattrs[i] = kmalloc(sizeof(struct ceph_inode_xattr),
                        GFP_NOFS);
            if (!xattrs[i])
                goto bad_lock;
        }

        spin_lock(&ci->i_ceph_lock);
        if (ci->i_xattrs.version != xattr_version) {
            /* lost a race, retry */
            for (i = 0; i < numattr; i++)
                kfree(xattrs[i]);
            kfree(xattrs);
            xattrs = NULL;
            goto start;
        }
        err = -EIO;
        while (numattr--) {
            ceph_decode_32_safe(&p, end, len, bad);
            namelen = len;
            name = p;
            p += len;
            ceph_decode_32_safe(&p, end, len, bad);
            val = p;
            p += len;

            err = __set_xattr(ci, name, namelen, val, len,
                      0, 0, 0, &xattrs[numattr]);

            if (err < 0)
                goto bad;
        }
        kfree(xattrs);
    }
    ci->i_xattrs.index_version = ci->i_xattrs.version;
    ci->i_xattrs.dirty = false;

    return err;
bad_lock:
    spin_lock(&ci->i_ceph_lock);
bad:
    if (xattrs) {
        for (i = 0; i < numattr; i++)
            kfree(xattrs[i]);
        kfree(xattrs);
    }
    ci->i_xattrs.names_size = 0;
    return err;
}

static int __get_required_blob_size(struct ceph_inode_info *ci, int name_size,
                    int val_size)
{
    /*
     * 4 bytes for the length, and additional 4 bytes per each xattr name,
     * 4 bytes per each value
     */
    int size = 4 + ci->i_xattrs.count*(4 + 4) +
                 ci->i_xattrs.names_size +
                 ci->i_xattrs.vals_size;
    dout("__get_required_blob_size c=%d names.size=%d vals.size=%d\n",
         ci->i_xattrs.count, ci->i_xattrs.names_size,
         ci->i_xattrs.vals_size);

    if (name_size)
        size += 4 + 4 + name_size + val_size;

    return size;
}

/*
 * If there are dirty xattrs, reencode xattrs into the prealloc_blob
 * and swap into place.
 */
void __ceph_build_xattrs_blob(struct ceph_inode_info *ci)
{
    struct rb_node *p;
    struct ceph_inode_xattr *xattr = NULL;
    void *dest;

    dout("__build_xattrs_blob %p\n", &ci->vfs_inode);
    if (ci->i_xattrs.dirty) {
        int need = __get_required_blob_size(ci, 0, 0);

        BUG_ON(need > ci->i_xattrs.prealloc_blob->alloc_len);

        p = rb_first(&ci->i_xattrs.index);
        dest = ci->i_xattrs.prealloc_blob->vec.iov_base;

        ceph_encode_32(&dest, ci->i_xattrs.count);
        while (p) {
            xattr = rb_entry(p, struct ceph_inode_xattr, node);

            ceph_encode_32(&dest, xattr->name_len);
            memcpy(dest, xattr->name, xattr->name_len);
            dest += xattr->name_len;
            ceph_encode_32(&dest, xattr->val_len);
            memcpy(dest, xattr->val, xattr->val_len);
            dest += xattr->val_len;

            p = rb_next(p);
        }

        /* adjust buffer len; it may be larger than we need */
        ci->i_xattrs.prealloc_blob->vec.iov_len =
            dest - ci->i_xattrs.prealloc_blob->vec.iov_base;

        if (ci->i_xattrs.blob)
            ceph_buffer_put(ci->i_xattrs.blob);
        ci->i_xattrs.blob = ci->i_xattrs.prealloc_blob;
        ci->i_xattrs.prealloc_blob = NULL;
        ci->i_xattrs.dirty = false;
        ci->i_xattrs.version++;
    }
}

ssize_t ceph_getxattr(struct dentry *dentry, const char *name, void *value,
              size_t size)
{
    struct inode *inode = dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    int err;
    struct ceph_inode_xattr *xattr;
    struct ceph_vxattr *vxattr = NULL;

    if (!ceph_is_valid_xattr(name))
        return -ENODATA;

    /* let's see if a virtual xattr was requested */
    vxattr = ceph_match_vxattr(inode, name);

    spin_lock(&ci->i_ceph_lock);
    dout("getxattr %p ver=%lld index_ver=%lld\n", inode,
         ci->i_xattrs.version, ci->i_xattrs.index_version);

    if (__ceph_caps_issued_mask(ci, CEPH_CAP_XATTR_SHARED, 1) &&
        (ci->i_xattrs.index_version >= ci->i_xattrs.version)) {
        goto get_xattr;
    } else {
        spin_unlock(&ci->i_ceph_lock);
        /* get xattrs from mds (if we don't already have them) */
        err = ceph_do_getattr(inode, CEPH_STAT_CAP_XATTR);
        if (err)
            return err;
    }

    spin_lock(&ci->i_ceph_lock);

    if (vxattr && vxattr->readonly) {
        err = vxattr->getxattr_cb(ci, value, size);
        goto out;
    }

    err = __build_xattrs(inode);
    if (err < 0)
        goto out;

get_xattr:
    err = -ENODATA;  /* == ENOATTR */
    xattr = __get_xattr(ci, name);
    if (!xattr) {
        if (vxattr)
            err = vxattr->getxattr_cb(ci, value, size);
        goto out;
    }

    err = -ERANGE;
    if (size && size < xattr->val_len)
        goto out;

    err = xattr->val_len;
    if (size == 0)
        goto out;

    memcpy(value, xattr->val, xattr->val_len);

out:
    spin_unlock(&ci->i_ceph_lock);
    return err;
}

ssize_t ceph_listxattr(struct dentry *dentry, char *names, size_t size)
{
    struct inode *inode = dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    struct ceph_vxattr *vxattrs = ceph_inode_vxattrs(inode);
    u32 vir_namelen = 0;
    u32 namelen;
    int err;
    u32 len;
    int i;

    spin_lock(&ci->i_ceph_lock);
    dout("listxattr %p ver=%lld index_ver=%lld\n", inode,
         ci->i_xattrs.version, ci->i_xattrs.index_version);

    if (__ceph_caps_issued_mask(ci, CEPH_CAP_XATTR_SHARED, 1) &&
        (ci->i_xattrs.index_version >= ci->i_xattrs.version)) {
        goto list_xattr;
    } else {
        spin_unlock(&ci->i_ceph_lock);
        err = ceph_do_getattr(inode, CEPH_STAT_CAP_XATTR);
        if (err)
            return err;
    }

    spin_lock(&ci->i_ceph_lock);

    err = __build_xattrs(inode);
    if (err < 0)
        goto out;

list_xattr:
    /*
     * Start with virtual dir xattr names (if any) (including
     * terminating '\0' characters for each).
     */
    vir_namelen = ceph_vxattrs_name_size(vxattrs);

    /* adding 1 byte per each variable due to the null termination */
    namelen = vir_namelen + ci->i_xattrs.names_size + ci->i_xattrs.count;
    err = -ERANGE;
    if (size && namelen > size)
        goto out;

    err = namelen;
    if (size == 0)
        goto out;

    names = __copy_xattr_names(ci, names);

    /* virtual xattr names, too */
    if (vxattrs)
        for (i = 0; vxattrs[i].name; i++) {
            len = sprintf(names, "%s", vxattrs[i].name);
            names += len + 1;
        }

out:
    spin_unlock(&ci->i_ceph_lock);
    return err;
}

static int ceph_sync_setxattr(struct dentry *dentry, const char *name,
                  const char *value, size_t size, int flags)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
    struct inode *inode = dentry->d_inode;
    struct ceph_inode_info *ci = ceph_inode(inode);
    struct inode *parent_inode;
    struct ceph_mds_request *req;
    struct ceph_mds_client *mdsc = fsc->mdsc;
    int err;
    int i, nr_pages;
    struct page **pages = NULL;
    void *kaddr;

    /* copy value into some pages */
    nr_pages = calc_pages_for(0, size);
    if (nr_pages) {
        pages = kmalloc(sizeof(pages[0])*nr_pages, GFP_NOFS);
        if (!pages)
            return -ENOMEM;
        err = -ENOMEM;
        for (i = 0; i < nr_pages; i++) {
            pages[i] = __page_cache_alloc(GFP_NOFS);
            if (!pages[i]) {
                nr_pages = i;
                goto out;
            }
            kaddr = kmap(pages[i]);
            memcpy(kaddr, value + i*PAGE_CACHE_SIZE,
                   min(PAGE_CACHE_SIZE, size-i*PAGE_CACHE_SIZE));
        }
    }

    dout("setxattr value=%.*s\n", (int)size, value);

    /* do request */
    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETXATTR,
                       USE_AUTH_MDS);
    if (IS_ERR(req)) {
        err = PTR_ERR(req);
        goto out;
    }
    req->r_inode = inode;
    ihold(inode);
    req->r_inode_drop = CEPH_CAP_XATTR_SHARED;
    req->r_num_caps = 1;
    req->r_args.setxattr.flags = cpu_to_le32(flags);
    req->r_path2 = kstrdup(name, GFP_NOFS);

    req->r_pages = pages;
    req->r_num_pages = nr_pages;
    req->r_data_len = size;

    dout("xattr.ver (before): %lld\n", ci->i_xattrs.version);
    parent_inode = ceph_get_dentry_parent_inode(dentry);
    err = ceph_mdsc_do_request(mdsc, parent_inode, req);
    iput(parent_inode);
    ceph_mdsc_put_request(req);
    dout("xattr.ver (after): %lld\n", ci->i_xattrs.version);

out:
    if (pages) {
        for (i = 0; i < nr_pages; i++)
            __free_page(pages[i]);
        kfree(pages);
    }
    return err;
}

int ceph_setxattr(struct dentry *dentry, const char *name,
          const void *value, size_t size, int flags)
{
    struct inode *inode = dentry->d_inode;
    struct ceph_vxattr *vxattr;
    struct ceph_inode_info *ci = ceph_inode(inode);
    int issued;
    int err;
    int dirty;
    int name_len = strlen(name);
    int val_len = size;
    char *newname = NULL;
    char *newval = NULL;
    struct ceph_inode_xattr *xattr = NULL;
    int required_blob_size;

    if (ceph_snap(inode) != CEPH_NOSNAP)
        return -EROFS;

    if (!ceph_is_valid_xattr(name))
        return -EOPNOTSUPP;

    vxattr = ceph_match_vxattr(inode, name);
    if (vxattr && vxattr->readonly)
        return -EOPNOTSUPP;

    /* preallocate memory for xattr name, value, index node */
    err = -ENOMEM;
    newname = kmemdup(name, name_len + 1, GFP_NOFS);
    if (!newname)
        goto out;

    if (val_len) {
        newval = kmemdup(value, val_len, GFP_NOFS);
        if (!newval)
            goto out;
    }

    xattr = kmalloc(sizeof(struct ceph_inode_xattr), GFP_NOFS);
    if (!xattr)
        goto out;

    spin_lock(&ci->i_ceph_lock);
retry:
    issued = __ceph_caps_issued(ci, NULL);
    dout("setxattr %p issued %s\n", inode, ceph_cap_string(issued));
    if (!(issued & CEPH_CAP_XATTR_EXCL))
        goto do_sync;
    __build_xattrs(inode);

    required_blob_size = __get_required_blob_size(ci, name_len, val_len);

    if (!ci->i_xattrs.prealloc_blob ||
        required_blob_size > ci->i_xattrs.prealloc_blob->alloc_len) {
        struct ceph_buffer *blob;

        spin_unlock(&ci->i_ceph_lock);
        dout(" preaallocating new blob size=%d\n", required_blob_size);
        blob = ceph_buffer_new(required_blob_size, GFP_NOFS);
        if (!blob)
            goto out;
        spin_lock(&ci->i_ceph_lock);
        if (ci->i_xattrs.prealloc_blob)
            ceph_buffer_put(ci->i_xattrs.prealloc_blob);
        ci->i_xattrs.prealloc_blob = blob;
        goto retry;
    }

    err = __set_xattr(ci, newname, name_len, newval,
              val_len, 1, 1, 1, &xattr);

    dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_XATTR_EXCL);
    ci->i_xattrs.dirty = true;
    inode->i_ctime = CURRENT_TIME;

    spin_unlock(&ci->i_ceph_lock);
    if (dirty)
        __mark_inode_dirty(inode, dirty);
    return err;

do_sync:
    spin_unlock(&ci->i_ceph_lock);
    err = ceph_sync_setxattr(dentry, name, value, size, flags);
out:
    kfree(newname);
    kfree(newval);
    kfree(xattr);
    return err;
}

static int ceph_send_removexattr(struct dentry *dentry, const char *name)
{
    struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
    struct ceph_mds_client *mdsc = fsc->mdsc;
    struct inode *inode = dentry->d_inode;
    struct inode *parent_inode;
    struct ceph_mds_request *req;
    int err;

    req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_RMXATTR,
                       USE_AUTH_MDS);
    if (IS_ERR(req))
        return PTR_ERR(req);
    req->r_inode = inode;
    ihold(inode);
    req->r_inode_drop = CEPH_CAP_XATTR_SHARED;
    req->r_num_caps = 1;
    req->r_path2 = kstrdup(name, GFP_NOFS);

    parent_inode = ceph_get_dentry_parent_inode(dentry);
    err = ceph_mdsc_do_request(mdsc, parent_inode, req);
    iput(parent_inode);
    ceph_mdsc_put_request(req);
    return err;
}

int ceph_removexattr(struct dentry *dentry, const char *name)
{
    struct inode *inode = dentry->d_inode;
    struct ceph_vxattr *vxattr;
    struct ceph_inode_info *ci = ceph_inode(inode);
    int issued;
    int err;
    int required_blob_size;
    int dirty;

    if (ceph_snap(inode) != CEPH_NOSNAP)
        return -EROFS;

    if (!ceph_is_valid_xattr(name))
        return -EOPNOTSUPP;

    vxattr = ceph_match_vxattr(inode, name);
    if (vxattr && vxattr->readonly)
        return -EOPNOTSUPP;

    err = -ENOMEM;
    spin_lock(&ci->i_ceph_lock);
retry:
    issued = __ceph_caps_issued(ci, NULL);
    dout("removexattr %p issued %s\n", inode, ceph_cap_string(issued));

    if (!(issued & CEPH_CAP_XATTR_EXCL))
        goto do_sync;
    __build_xattrs(inode);

    required_blob_size = __get_required_blob_size(ci, 0, 0);

    if (!ci->i_xattrs.prealloc_blob ||
        required_blob_size > ci->i_xattrs.prealloc_blob->alloc_len) {
        struct ceph_buffer *blob;

        spin_unlock(&ci->i_ceph_lock);
        dout(" preaallocating new blob size=%d\n", required_blob_size);
        blob = ceph_buffer_new(required_blob_size, GFP_NOFS);
        if (!blob)
            goto out;
        spin_lock(&ci->i_ceph_lock);
        if (ci->i_xattrs.prealloc_blob)
            ceph_buffer_put(ci->i_xattrs.prealloc_blob);
        ci->i_xattrs.prealloc_blob = blob;
        goto retry;
    }

    err = __remove_xattr_by_name(ceph_inode(inode), name);

    dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_XATTR_EXCL);
    ci->i_xattrs.dirty = true;
    inode->i_ctime = CURRENT_TIME;
    spin_unlock(&ci->i_ceph_lock);
    if (dirty)
        __mark_inode_dirty(inode, dirty);
    return err;
do_sync:
    spin_unlock(&ci->i_ceph_lock);
    err = ceph_send_removexattr(dentry, name);
out:
    return err;
}