[safe/jmp/linux-2.6] / fs / exofs / inode.c

/*
 * Copyright (C) 2005, 2006
 * Avishay Traeger (avishay@gmail.com)
 * Copyright (C) 2008, 2009
 * Boaz Harrosh <bharrosh@panasas.com>
 *
 * Copyrights for code taken from ext2:
 *     Copyright (C) 1992, 1993, 1994, 1995
 *     Remy Card (card@masi.ibp.fr)
 *     Laboratoire MASI - Institut Blaise Pascal
 *     Universite Pierre et Marie Curie (Paris VI)
 *     from
 *     linux/fs/minix/inode.c
 *     Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is part of exofs.
 *
 * exofs 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.  Since it is based on ext2, and the only
 * valid version of GPL for the Linux kernel is version 2, the only valid
 * version of GPL for exofs is version 2.
 *
 * exofs 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 exofs; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <scsi/scsi_device.h>

#include "exofs.h"

#define EXOFS_DBGMSG2(M...) do {} while (0)

enum { BIO_MAX_PAGES_KMALLOC =
                (PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),
};

struct page_collect {
        struct exofs_sb_info *sbi;
        struct request_queue *req_q;
        struct inode *inode;
        unsigned expected_pages;
        struct exofs_io_state *ios;

        struct bio *bio;
        unsigned nr_pages;
        unsigned long length;
        loff_t pg_first; /* keep 64bit also in 32-arches */
};

static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,
                       struct inode *inode)
{
        struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;

        pcol->sbi = sbi;
        /* Create master bios on first Q, later on cloning, each clone will be
         * allocated on it's destination Q
         */
        pcol->req_q = osd_request_queue(sbi->layout.s_ods[0]);
        pcol->inode = inode;
        pcol->expected_pages = expected_pages;

        pcol->ios = NULL;
        pcol->bio = NULL;
        pcol->nr_pages = 0;
        pcol->length = 0;
        pcol->pg_first = -1;
}

static void _pcol_reset(struct page_collect *pcol)
{
        pcol->expected_pages -= min(pcol->nr_pages, pcol->expected_pages);

        pcol->bio = NULL;
        pcol->nr_pages = 0;
        pcol->length = 0;
        pcol->pg_first = -1;
        pcol->ios = NULL;

        /* this is probably the end of the loop but in writes
         * it might not end here. don't be left with nothing
         */
        if (!pcol->expected_pages)
                pcol->expected_pages = BIO_MAX_PAGES_KMALLOC;
}

static int pcol_try_alloc(struct page_collect *pcol)
{
        int pages = min_t(unsigned, pcol->expected_pages,
                          BIO_MAX_PAGES_KMALLOC);

        if (!pcol->ios) { /* First time allocate io_state */
                int ret = exofs_get_io_state(&pcol->sbi->layout, &pcol->ios);

                if (ret)
                        return ret;
        }

        for (; pages; pages >>= 1) {
                pcol->bio = bio_kmalloc(GFP_KERNEL, pages);
                if (likely(pcol->bio))
                        return 0;
        }

        EXOFS_ERR("Failed to bio_kmalloc expected_pages=%u\n",
                  pcol->expected_pages);
        return -ENOMEM;
}

static void pcol_free(struct page_collect *pcol)
{
        if (pcol->bio) {
                bio_put(pcol->bio);
                pcol->bio = NULL;
        }

        if (pcol->ios) {
                exofs_put_io_state(pcol->ios);
                pcol->ios = NULL;
        }
}

static int pcol_add_page(struct page_collect *pcol, struct page *page,
                         unsigned len)
{
        int added_len = bio_add_pc_page(pcol->req_q, pcol->bio, page, len, 0);
        if (unlikely(len != added_len))
                return -ENOMEM;

        ++pcol->nr_pages;
        pcol->length += len;
        return 0;
}

static int update_read_page(struct page *page, int ret)
{
        if (ret == 0) {
                /* Everything is OK */
                SetPageUptodate(page);
                if (PageError(page))
                        ClearPageError(page);
        } else if (ret == -EFAULT) {
                /* In this case we were trying to read something that wasn't on
                 * disk yet - return a page full of zeroes.  This should be OK,
                 * because the object should be empty (if there was a write
                 * before this read, the read would be waiting with the page
                 * locked */
                clear_highpage(page);

                SetPageUptodate(page);
                if (PageError(page))
                        ClearPageError(page);
                ret = 0; /* recovered error */
                EXOFS_DBGMSG("recovered read error\n");
        } else /* Error */
                SetPageError(page);

        return ret;
}

static void update_write_page(struct page *page, int ret)
{
        if (ret) {
                mapping_set_error(page->mapping, ret);
                SetPageError(page);
        }
        end_page_writeback(page);
}

/* Called at the end of reads, to optionally unlock pages and update their
 * status.
 */
static int __readpages_done(struct page_collect *pcol, bool do_unlock)
{
        struct bio_vec *bvec;
        int i;
        u64 resid;
        u64 good_bytes;
        u64 length = 0;
        int ret = exofs_check_io(pcol->ios, &resid);

        if (likely(!ret))
                good_bytes = pcol->length;
        else
                good_bytes = pcol->length - resid;

        EXOFS_DBGMSG2("readpages_done(0x%lx) good_bytes=0x%llx"
                     " length=0x%lx nr_pages=%u\n",
                     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
                     pcol->nr_pages);

        __bio_for_each_segment(bvec, pcol->bio, i, 0) {
                struct page *page = bvec->bv_page;
                struct inode *inode = page->mapping->host;
                int page_stat;

                if (inode != pcol->inode)
                        continue; /* osd might add more pages at end */

                if (likely(length < good_bytes))
                        page_stat = 0;
                else
                        page_stat = ret;

                EXOFS_DBGMSG2("    readpages_done(0x%lx, 0x%lx) %s\n",
                          inode->i_ino, page->index,
                          page_stat ? "bad_bytes" : "good_bytes");

                ret = update_read_page(page, page_stat);
                if (do_unlock)
                        unlock_page(page);
                length += bvec->bv_len;
        }

        pcol_free(pcol);
        EXOFS_DBGMSG2("readpages_done END\n");
        return ret;
}

/* callback of async reads */
static void readpages_done(struct exofs_io_state *ios, void *p)
{
        struct page_collect *pcol = p;

        __readpages_done(pcol, true);
        atomic_dec(&pcol->sbi->s_curr_pending);
        kfree(pcol);
}

static void _unlock_pcol_pages(struct page_collect *pcol, int ret, int rw)
{
        struct bio_vec *bvec;
        int i;

        __bio_for_each_segment(bvec, pcol->bio, i, 0) {
                struct page *page = bvec->bv_page;

                if (rw == READ)
                        update_read_page(page, ret);
                else
                        update_write_page(page, ret);

                unlock_page(page);
        }
}

static int read_exec(struct page_collect *pcol, bool is_sync)
{
        struct exofs_i_info *oi = exofs_i(pcol->inode);
        struct exofs_io_state *ios = pcol->ios;
        struct page_collect *pcol_copy = NULL;
        int ret;

        if (!pcol->bio)
                return 0;

        /* see comment in _readpage() about sync reads */
        WARN_ON(is_sync && (pcol->nr_pages != 1));

        ios->bio = pcol->bio;
        ios->length = pcol->length;
        ios->offset = pcol->pg_first << PAGE_CACHE_SHIFT;

        if (is_sync) {
                exofs_oi_read(oi, pcol->ios);
                return __readpages_done(pcol, false);
        }

        pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
        if (!pcol_copy) {
                ret = -ENOMEM;
                goto err;
        }

        *pcol_copy = *pcol;
        ios->done = readpages_done;
        ios->private = pcol_copy;
        ret = exofs_oi_read(oi, ios);
        if (unlikely(ret))
                goto err;

        atomic_inc(&pcol->sbi->s_curr_pending);

        EXOFS_DBGMSG2("read_exec obj=0x%llx start=0x%llx length=0x%lx\n",
                  ios->obj.id, _LLU(ios->offset), pcol->length);

        /* pages ownership was passed to pcol_copy */
        _pcol_reset(pcol);
        return 0;

err:
        if (!is_sync)
                _unlock_pcol_pages(pcol, ret, READ);

        pcol_free(pcol);

        kfree(pcol_copy);
        return ret;
}

/* readpage_strip is called either directly from readpage() or by the VFS from
 * within read_cache_pages(), to add one more page to be read. It will try to
 * collect as many contiguous pages as posible. If a discontinuity is
 * encountered, or it runs out of resources, it will submit the previous segment
 * and will start a new collection. Eventually caller must submit the last
 * segment if present.
 */
static int readpage_strip(void *data, struct page *page)
{
        struct page_collect *pcol = data;
        struct inode *inode = pcol->inode;
        struct exofs_i_info *oi = exofs_i(inode);
        loff_t i_size = i_size_read(inode);
        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
        size_t len;
        int ret;

        /* FIXME: Just for debugging, will be removed */
        if (PageUptodate(page))
                EXOFS_ERR("PageUptodate(0x%lx, 0x%lx)\n", pcol->inode->i_ino,
                          page->index);

        if (page->index < end_index)
                len = PAGE_CACHE_SIZE;
        else if (page->index == end_index)
                len = i_size & ~PAGE_CACHE_MASK;
        else
                len = 0;

        if (!len || !obj_created(oi)) {
                /* this will be out of bounds, or doesn't exist yet.
                 * Current page is cleared and the request is split
                 */
                clear_highpage(page);

                SetPageUptodate(page);
                if (PageError(page))
                        ClearPageError(page);

                unlock_page(page);
                EXOFS_DBGMSG("readpage_strip(0x%lx, 0x%lx) empty page,"
                             " splitting\n", inode->i_ino, page->index);

                return read_exec(pcol, false);
        }

try_again:

        if (unlikely(pcol->pg_first == -1)) {
                pcol->pg_first = page->index;
        } else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
                   page->index)) {
                /* Discontinuity detected, split the request */
                ret = read_exec(pcol, false);
                if (unlikely(ret))
                        goto fail;
                goto try_again;
        }

        if (!pcol->bio) {
                ret = pcol_try_alloc(pcol);
                if (unlikely(ret))
                        goto fail;
        }

        if (len != PAGE_CACHE_SIZE)
                zero_user(page, len, PAGE_CACHE_SIZE - len);

        EXOFS_DBGMSG2("    readpage_strip(0x%lx, 0x%lx) len=0x%zx\n",
                     inode->i_ino, page->index, len);

        ret = pcol_add_page(pcol, page, len);
        if (ret) {
                EXOFS_DBGMSG2("Failed pcol_add_page pages[i]=%p "
                          "this_len=0x%zx nr_pages=%u length=0x%lx\n",
                          page, len, pcol->nr_pages, pcol->length);

                /* split the request, and start again with current page */
                ret = read_exec(pcol, false);
                if (unlikely(ret))
                        goto fail;

                goto try_again;
        }

        return 0;

fail:
        /* SetPageError(page); ??? */
        unlock_page(page);
        return ret;
}

static int exofs_readpages(struct file *file, struct address_space *mapping,
                           struct list_head *pages, unsigned nr_pages)
{
        struct page_collect pcol;
        int ret;

        _pcol_init(&pcol, nr_pages, mapping->host);

        ret = read_cache_pages(mapping, pages, readpage_strip, &pcol);
        if (ret) {
                EXOFS_ERR("read_cache_pages => %d\n", ret);
                return ret;
        }

        return read_exec(&pcol, false);
}

static int _readpage(struct page *page, bool is_sync)
{
        struct page_collect pcol;
        int ret;

        _pcol_init(&pcol, 1, page->mapping->host);

        /* readpage_strip might call read_exec(,is_sync==false) at several
         * places but not if we have a single page.
         */
        ret = readpage_strip(&pcol, page);
        if (ret) {
                EXOFS_ERR("_readpage => %d\n", ret);
                return ret;
        }

        return read_exec(&pcol, is_sync);
}

/*
 * We don't need the file
 */
static int exofs_readpage(struct file *file, struct page *page)
{
        return _readpage(page, false);
}

/* Callback for osd_write. All writes are asynchronous */
static void writepages_done(struct exofs_io_state *ios, void *p)
{
        struct page_collect *pcol = p;
        struct bio_vec *bvec;
        int i;
        u64 resid;
        u64  good_bytes;
        u64  length = 0;
        int ret = exofs_check_io(ios, &resid);

        atomic_dec(&pcol->sbi->s_curr_pending);

        if (likely(!ret))
                good_bytes = pcol->length;
        else
                good_bytes = pcol->length - resid;

        EXOFS_DBGMSG2("writepages_done(0x%lx) good_bytes=0x%llx"
                     " length=0x%lx nr_pages=%u\n",
                     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
                     pcol->nr_pages);

        __bio_for_each_segment(bvec, pcol->bio, i, 0) {
                struct page *page = bvec->bv_page;
                struct inode *inode = page->mapping->host;
                int page_stat;

                if (inode != pcol->inode)
                        continue; /* osd might add more pages to a bio */

                if (likely(length < good_bytes))
                        page_stat = 0;
                else
                        page_stat = ret;

                update_write_page(page, page_stat);
                unlock_page(page);
                EXOFS_DBGMSG2("    writepages_done(0x%lx, 0x%lx) status=%d\n",
                             inode->i_ino, page->index, page_stat);

                length += bvec->bv_len;
        }

        pcol_free(pcol);
        kfree(pcol);
        EXOFS_DBGMSG2("writepages_done END\n");
}

static int write_exec(struct page_collect *pcol)
{
        struct exofs_i_info *oi = exofs_i(pcol->inode);
        struct exofs_io_state *ios = pcol->ios;
        struct page_collect *pcol_copy = NULL;
        int ret;

        if (!pcol->bio)
                return 0;

        pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
        if (!pcol_copy) {
                EXOFS_ERR("write_exec: Faild to kmalloc(pcol)\n");
                ret = -ENOMEM;
                goto err;
        }

        *pcol_copy = *pcol;

        pcol_copy->bio->bi_rw |= (1 << BIO_RW); /* FIXME: bio_set_dir() */

        ios->bio = pcol_copy->bio;
        ios->offset = pcol_copy->pg_first << PAGE_CACHE_SHIFT;
        ios->length = pcol_copy->length;
        ios->done = writepages_done;
        ios->private = pcol_copy;

        ret = exofs_oi_write(oi, ios);
        if (unlikely(ret)) {
                EXOFS_ERR("write_exec: exofs_oi_write() Faild\n");
                goto err;
        }

        atomic_inc(&pcol->sbi->s_curr_pending);
        EXOFS_DBGMSG2("write_exec(0x%lx, 0x%llx) start=0x%llx length=0x%lx\n",
                  pcol->inode->i_ino, pcol->pg_first, _LLU(ios->offset),
                  pcol->length);
        /* pages ownership was passed to pcol_copy */
        _pcol_reset(pcol);
        return 0;

err:
        _unlock_pcol_pages(pcol, ret, WRITE);
        pcol_free(pcol);
        kfree(pcol_copy);

        return ret;
}

/* writepage_strip is called either directly from writepage() or by the VFS from
 * within write_cache_pages(), to add one more page to be written to storage.
 * It will try to collect as many contiguous pages as possible. If a
 * discontinuity is encountered or it runs out of resources it will submit the
 * previous segment and will start a new collection.
 * Eventually caller must submit the last segment if present.
 */
static int writepage_strip(struct page *page,
                           struct writeback_control *wbc_unused, void *data)
{
        struct page_collect *pcol = data;
        struct inode *inode = pcol->inode;
        struct exofs_i_info *oi = exofs_i(inode);
        loff_t i_size = i_size_read(inode);
        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
        size_t len;
        int ret;

        BUG_ON(!PageLocked(page));

        ret = wait_obj_created(oi);
        if (unlikely(ret))
                goto fail;

        if (page->index < end_index)
                /* in this case, the page is within the limits of the file */
                len = PAGE_CACHE_SIZE;
        else {
                len = i_size & ~PAGE_CACHE_MASK;

                if (page->index > end_index || !len) {
                        /* in this case, the page is outside the limits
                         * (truncate in progress)
                         */
                        ret = write_exec(pcol);
                        if (unlikely(ret))
                                goto fail;
                        if (PageError(page))
                                ClearPageError(page);
                        unlock_page(page);
                        EXOFS_DBGMSG("writepage_strip(0x%lx, 0x%lx) "
                                     "outside the limits\n",
                                     inode->i_ino, page->index);
                        return 0;
                }
        }

try_again:

        if (unlikely(pcol->pg_first == -1)) {
                pcol->pg_first = page->index;
        } else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
                   page->index)) {
                /* Discontinuity detected, split the request */
                ret = write_exec(pcol);
                if (unlikely(ret))
                        goto fail;

                EXOFS_DBGMSG("writepage_strip(0x%lx, 0x%lx) Discontinuity\n",
                             inode->i_ino, page->index);
                goto try_again;
        }

        if (!pcol->bio) {
                ret = pcol_try_alloc(pcol);
                if (unlikely(ret))
                        goto fail;
        }

        EXOFS_DBGMSG2("    writepage_strip(0x%lx, 0x%lx) len=0x%zx\n",
                     inode->i_ino, page->index, len);

        ret = pcol_add_page(pcol, page, len);
        if (unlikely(ret)) {
                EXOFS_DBGMSG2("Failed pcol_add_page "
                             "nr_pages=%u total_length=0x%lx\n",
                             pcol->nr_pages, pcol->length);

                /* split the request, next loop will start again */
                ret = write_exec(pcol);
                if (unlikely(ret)) {
                        EXOFS_DBGMSG("write_exec faild => %d", ret);
                        goto fail;
                }

                goto try_again;
        }

        BUG_ON(PageWriteback(page));
        set_page_writeback(page);

        return 0;

fail:
        EXOFS_DBGMSG("Error: writepage_strip(0x%lx, 0x%lx)=>%d\n",
                     inode->i_ino, page->index, ret);
        set_bit(AS_EIO, &page->mapping->flags);
        unlock_page(page);
        return ret;
}

static int exofs_writepages(struct address_space *mapping,
                       struct writeback_control *wbc)
{
        struct page_collect pcol;
        long start, end, expected_pages;
        int ret;

        start = wbc->range_start >> PAGE_CACHE_SHIFT;
        end = (wbc->range_end == LLONG_MAX) ?
                        start + mapping->nrpages :
                        wbc->range_end >> PAGE_CACHE_SHIFT;

        if (start || end)
                expected_pages = end - start + 1;
        else
                expected_pages = mapping->nrpages;

        if (expected_pages < 32L)
                expected_pages = 32L;

        EXOFS_DBGMSG2("inode(0x%lx) wbc->start=0x%llx wbc->end=0x%llx "
                     "nrpages=%lu start=0x%lx end=0x%lx expected_pages=%ld\n",
                     mapping->host->i_ino, wbc->range_start, wbc->range_end,
                     mapping->nrpages, start, end, expected_pages);

        _pcol_init(&pcol, expected_pages, mapping->host);

        ret = write_cache_pages(mapping, wbc, writepage_strip, &pcol);
        if (ret) {
                EXOFS_ERR("write_cache_pages => %d\n", ret);
                return ret;
        }

        return write_exec(&pcol);
}

static int exofs_writepage(struct page *page, struct writeback_control *wbc)
{
        struct page_collect pcol;
        int ret;

        _pcol_init(&pcol, 1, page->mapping->host);

        ret = writepage_strip(page, NULL, &pcol);
        if (ret) {
                EXOFS_ERR("exofs_writepage => %d\n", ret);
                return ret;
        }

        return write_exec(&pcol);
}

int exofs_write_begin(struct file *file, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata)
{
        int ret = 0;
        struct page *page;

        page = *pagep;
        if (page == NULL) {
                ret = simple_write_begin(file, mapping, pos, len, flags, pagep,
                                         fsdata);
                if (ret) {
                        EXOFS_DBGMSG("simple_write_begin faild\n");
                        return ret;
                }

                page = *pagep;
        }

         /* read modify write */
        if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
                ret = _readpage(page, true);
                if (ret) {
                        /*SetPageError was done by _readpage. Is it ok?*/
                        unlock_page(page);
                        EXOFS_DBGMSG("__readpage_filler faild\n");
                }
        }

        return ret;
}

static int exofs_write_begin_export(struct file *file,
                struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata)
{
        *pagep = NULL;

        return exofs_write_begin(file, mapping, pos, len, flags, pagep,
                                        fsdata);
}

static int exofs_write_end(struct file *file, struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned copied,
                        struct page *page, void *fsdata)
{
        struct inode *inode = mapping->host;
        /* According to comment in simple_write_end i_mutex is held */
        loff_t i_size = inode->i_size;
        int ret;

        ret = simple_write_end(file, mapping,pos, len, copied, page, fsdata);
        if (i_size != inode->i_size)
                mark_inode_dirty(inode);
        return ret;
}

const struct address_space_operations exofs_aops = {
        .readpage       = exofs_readpage,
        .readpages      = exofs_readpages,
        .writepage      = exofs_writepage,
        .writepages     = exofs_writepages,
        .write_begin    = exofs_write_begin_export,
        .write_end      = exofs_write_end,
};

/******************************************************************************
 * INODE OPERATIONS
 *****************************************************************************/

/*
 * Test whether an inode is a fast symlink.
 */
static inline int exofs_inode_is_fast_symlink(struct inode *inode)
{
        struct exofs_i_info *oi = exofs_i(inode);

        return S_ISLNK(inode->i_mode) && (oi->i_data[0] != 0);
}

/*
 * get_block_t - Fill in a buffer_head
 * An OSD takes care of block allocation so we just fake an allocation by
 * putting in the inode's sector_t in the buffer_head.
 * TODO: What about the case of create==0 and @iblock does not exist in the
 * object?
 */
static int exofs_get_block(struct inode *inode, sector_t iblock,
                    struct buffer_head *bh_result, int create)
{
        map_bh(bh_result, inode->i_sb, iblock);
        return 0;
}

const struct osd_attr g_attr_logical_length = ATTR_DEF(
        OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);

static int _do_truncate(struct inode *inode)
{
        struct exofs_i_info *oi = exofs_i(inode);
        loff_t isize = i_size_read(inode);
        int ret;

        inode->i_mtime = inode->i_ctime = CURRENT_TIME;

        nobh_truncate_page(inode->i_mapping, isize, exofs_get_block);

        ret = exofs_oi_truncate(oi, (u64)isize);
        EXOFS_DBGMSG("(0x%lx) size=0x%llx\n", inode->i_ino, isize);
        return ret;
}

/*
 * Truncate a file to the specified size - all we have to do is set the size
 * attribute.  We make sure the object exists first.
 */
void exofs_truncate(struct inode *inode)
{
        struct exofs_i_info *oi = exofs_i(inode);
        int ret;

        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
             || S_ISLNK(inode->i_mode)))
                return;
        if (exofs_inode_is_fast_symlink(inode))
                return;
        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                return;

        /* if we are about to truncate an object, and it hasn't been
         * created yet, wait
         */
        if (unlikely(wait_obj_created(oi)))
                goto fail;

        ret = _do_truncate(inode);
        if (ret)
                goto fail;

out:
        mark_inode_dirty(inode);
        return;
fail:
        make_bad_inode(inode);
        goto out;
}

/*
 * Set inode attributes - just call generic functions.
 */
int exofs_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;

        error = inode_setattr(inode, iattr);
        return error;
}

static const struct osd_attr g_attr_inode_file_layout = ATTR_DEF(
        EXOFS_APAGE_FS_DATA,
        EXOFS_ATTR_INODE_FILE_LAYOUT,
        0);
static const struct osd_attr g_attr_inode_dir_layout = ATTR_DEF(
        EXOFS_APAGE_FS_DATA,
        EXOFS_ATTR_INODE_DIR_LAYOUT,
        0);

/*
 * Read an inode from the OSD, and return it as is.  We also return the size
 * attribute in the 'obj_size' argument.
 */
static int exofs_get_inode(struct super_block *sb, struct exofs_i_info *oi,
                    struct exofs_fcb *inode, uint64_t *obj_size)
{
        struct exofs_sb_info *sbi = sb->s_fs_info;
        struct osd_attr attrs[] = {
                [0] = g_attr_inode_data,
                [1] = g_attr_inode_file_layout,
                [2] = g_attr_inode_dir_layout,
                [3] = g_attr_logical_length,
        };
        struct exofs_io_state *ios;
        struct exofs_on_disk_inode_layout *layout;
        int ret;

        ret = exofs_get_io_state(&sbi->layout, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: exofs_get_io_state failed.\n", __func__);
                return ret;
        }

        ios->obj.id = exofs_oi_objno(oi);
        exofs_make_credential(oi->i_cred, &ios->obj);
        ios->cred = oi->i_cred;

        attrs[1].len = exofs_on_disk_inode_layout_size(sbi->layout.s_numdevs);
        attrs[2].len = exofs_on_disk_inode_layout_size(sbi->layout.s_numdevs);

        ios->in_attr = attrs;
        ios->in_attr_len = ARRAY_SIZE(attrs);

        ret = exofs_sbi_read(ios);
        if (ret)
                goto out;

        ret = extract_attr_from_ios(ios, &attrs[0]);
        if (ret) {
                EXOFS_ERR("%s: extract_attr of inode_data failed\n", __func__);
                goto out;
        }
        WARN_ON(attrs[0].len != EXOFS_INO_ATTR_SIZE);
        memcpy(inode, attrs[0].val_ptr, EXOFS_INO_ATTR_SIZE);

        ret = extract_attr_from_ios(ios, &attrs[1]);
        if (ret) {
                EXOFS_ERR("%s: extract_attr of inode_data failed\n", __func__);
                goto out;
        }
        if (attrs[1].len) {
                layout = attrs[1].val_ptr;
                if (layout->gen_func != cpu_to_le16(LAYOUT_MOVING_WINDOW)) {
                        EXOFS_ERR("%s: unsupported files layout %d\n",
                                __func__, layout->gen_func);
                        ret = -ENOTSUPP;
                        goto out;
                }
        }

        ret = extract_attr_from_ios(ios, &attrs[2]);
        if (ret) {
                EXOFS_ERR("%s: extract_attr of inode_data failed\n", __func__);
                goto out;
        }
        if (attrs[2].len) {
                layout = attrs[2].val_ptr;
                if (layout->gen_func != cpu_to_le16(LAYOUT_MOVING_WINDOW)) {
                        EXOFS_ERR("%s: unsupported meta-data layout %d\n",
                                __func__, layout->gen_func);
                        ret = -ENOTSUPP;
                        goto out;
                }
        }

        *obj_size = ~0;
        ret = extract_attr_from_ios(ios, &attrs[3]);
        if (ret) {
                EXOFS_ERR("%s: extract_attr of logical_length failed\n",
                          __func__);
                goto out;
        }
        *obj_size = get_unaligned_be64(attrs[3].val_ptr);

out:
        exofs_put_io_state(ios);
        return ret;
}

static void __oi_init(struct exofs_i_info *oi)
{
        init_waitqueue_head(&oi->i_wq);
        oi->i_flags = 0;
}
/*
 * Fill in an inode read from the OSD and set it up for use
 */
struct inode *exofs_iget(struct super_block *sb, unsigned long ino)
{
        struct exofs_i_info *oi;
        struct exofs_fcb fcb;
        struct inode *inode;
        uint64_t obj_size;
        int ret;

        inode = iget_locked(sb, ino);
        if (!inode)
                return ERR_PTR(-ENOMEM);
        if (!(inode->i_state & I_NEW))
                return inode;
        oi = exofs_i(inode);
        __oi_init(oi);

        /* read the inode from the osd */
        ret = exofs_get_inode(sb, oi, &fcb, &obj_size);
        if (ret)
                goto bad_inode;

        set_obj_created(oi);

        /* copy stuff from on-disk struct to in-memory struct */
        inode->i_mode = le16_to_cpu(fcb.i_mode);
        inode->i_uid = le32_to_cpu(fcb.i_uid);
        inode->i_gid = le32_to_cpu(fcb.i_gid);
        inode->i_nlink = le16_to_cpu(fcb.i_links_count);
        inode->i_ctime.tv_sec = (signed)le32_to_cpu(fcb.i_ctime);
        inode->i_atime.tv_sec = (signed)le32_to_cpu(fcb.i_atime);
        inode->i_mtime.tv_sec = (signed)le32_to_cpu(fcb.i_mtime);
        inode->i_ctime.tv_nsec =
                inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = 0;
        oi->i_commit_size = le64_to_cpu(fcb.i_size);
        i_size_write(inode, oi->i_commit_size);
        inode->i_blkbits = EXOFS_BLKSHIFT;
        inode->i_generation = le32_to_cpu(fcb.i_generation);

        if ((inode->i_size != obj_size) &&
                (!exofs_inode_is_fast_symlink(inode))) {
                EXOFS_ERR("WARNING: Size of inode=%llu != object=%llu\n",
                          inode->i_size, _LLU(obj_size));
                /* FIXME: call exofs_inode_recovery() */
        }

        oi->i_dir_start_lookup = 0;

        if ((inode->i_nlink == 0) && (inode->i_mode == 0)) {
                ret = -ESTALE;
                goto bad_inode;
        }

        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
                if (fcb.i_data[0])
                        inode->i_rdev =
                                old_decode_dev(le32_to_cpu(fcb.i_data[0]));
                else
                        inode->i_rdev =
                                new_decode_dev(le32_to_cpu(fcb.i_data[1]));
        } else {
                memcpy(oi->i_data, fcb.i_data, sizeof(fcb.i_data));
        }

        if (S_ISREG(inode->i_mode)) {
                inode->i_op = &exofs_file_inode_operations;
                inode->i_fop = &exofs_file_operations;
                inode->i_mapping->a_ops = &exofs_aops;
        } else if (S_ISDIR(inode->i_mode)) {
                inode->i_op = &exofs_dir_inode_operations;
                inode->i_fop = &exofs_dir_operations;
                inode->i_mapping->a_ops = &exofs_aops;
        } else if (S_ISLNK(inode->i_mode)) {
                if (exofs_inode_is_fast_symlink(inode))
                        inode->i_op = &exofs_fast_symlink_inode_operations;
                else {
                        inode->i_op = &exofs_symlink_inode_operations;
                        inode->i_mapping->a_ops = &exofs_aops;
                }
        } else {
                inode->i_op = &exofs_special_inode_operations;
                if (fcb.i_data[0])
                        init_special_inode(inode, inode->i_mode,
                           old_decode_dev(le32_to_cpu(fcb.i_data[0])));
                else
                        init_special_inode(inode, inode->i_mode,
                           new_decode_dev(le32_to_cpu(fcb.i_data[1])));
        }

        unlock_new_inode(inode);
        return inode;

bad_inode:
        iget_failed(inode);
        return ERR_PTR(ret);
}

int __exofs_wait_obj_created(struct exofs_i_info *oi)
{
        if (!obj_created(oi)) {
                BUG_ON(!obj_2bcreated(oi));
                wait_event(oi->i_wq, obj_created(oi));
        }
        return unlikely(is_bad_inode(&oi->vfs_inode)) ? -EIO : 0;
}
/*
 * Callback function from exofs_new_inode().  The important thing is that we
 * set the obj_created flag so that other methods know that the object exists on
 * the OSD.
 */
static void create_done(struct exofs_io_state *ios, void *p)
{
        struct inode *inode = p;
        struct exofs_i_info *oi = exofs_i(inode);
        struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
        int ret;

        ret = exofs_check_io(ios, NULL);
        exofs_put_io_state(ios);

        atomic_dec(&sbi->s_curr_pending);

        if (unlikely(ret)) {
                EXOFS_ERR("object=0x%llx creation faild in pid=0x%llx",
                          _LLU(exofs_oi_objno(oi)), _LLU(sbi->layout.s_pid));
                /*TODO: When FS is corrupted creation can fail, object already
                 * exist. Get rid of this asynchronous creation, if exist
                 * increment the obj counter and try the next object. Until we
                 * succeed. All these dangling objects will be made into lost
                 * files by chkfs.exofs
                 */
        }

        set_obj_created(oi);

        atomic_dec(&inode->i_count);
        wake_up(&oi->i_wq);
}

/*
 * Set up a new inode and create an object for it on the OSD
 */
struct inode *exofs_new_inode(struct inode *dir, int mode)
{
        struct super_block *sb;
        struct inode *inode;
        struct exofs_i_info *oi;
        struct exofs_sb_info *sbi;
        struct exofs_io_state *ios;
        int ret;

        sb = dir->i_sb;
        inode = new_inode(sb);
        if (!inode)
                return ERR_PTR(-ENOMEM);

        oi = exofs_i(inode);
        __oi_init(oi);

        set_obj_2bcreated(oi);

        sbi = sb->s_fs_info;

        sb->s_dirt = 1;
        inode->i_uid = current->cred->fsuid;
        if (dir->i_mode & S_ISGID) {
                inode->i_gid = dir->i_gid;
                if (S_ISDIR(mode))
                        mode |= S_ISGID;
        } else {
                inode->i_gid = current->cred->fsgid;
        }
        inode->i_mode = mode;

        inode->i_ino = sbi->s_nextid++;
        inode->i_blkbits = EXOFS_BLKSHIFT;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
        oi->i_commit_size = inode->i_size = 0;
        spin_lock(&sbi->s_next_gen_lock);
        inode->i_generation = sbi->s_next_generation++;
        spin_unlock(&sbi->s_next_gen_lock);
        insert_inode_hash(inode);

        mark_inode_dirty(inode);

        ret = exofs_get_io_state(&sbi->layout, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("exofs_new_inode: exofs_get_io_state failed\n");
                return ERR_PTR(ret);
        }

        ios->obj.id = exofs_oi_objno(oi);
        exofs_make_credential(oi->i_cred, &ios->obj);

        /* increment the refcount so that the inode will still be around when we
         * reach the callback
         */
        atomic_inc(&inode->i_count);

        ios->done = create_done;
        ios->private = inode;
        ios->cred = oi->i_cred;
        ret = exofs_sbi_create(ios);
        if (ret) {
                atomic_dec(&inode->i_count);
                exofs_put_io_state(ios);
                return ERR_PTR(ret);
        }
        atomic_inc(&sbi->s_curr_pending);

        return inode;
}

/*
 * struct to pass two arguments to update_inode's callback
 */
struct updatei_args {
        struct exofs_sb_info    *sbi;
        struct exofs_fcb        fcb;
};

/*
 * Callback function from exofs_update_inode().
 */
static void updatei_done(struct exofs_io_state *ios, void *p)
{
        struct updatei_args *args = p;

        exofs_put_io_state(ios);

        atomic_dec(&args->sbi->s_curr_pending);

        kfree(args);
}

/*
 * Write the inode to the OSD.  Just fill up the struct, and set the attribute
 * synchronously or asynchronously depending on the do_sync flag.
 */
static int exofs_update_inode(struct inode *inode, int do_sync)
{
        struct exofs_i_info *oi = exofs_i(inode);
        struct super_block *sb = inode->i_sb;
        struct exofs_sb_info *sbi = sb->s_fs_info;
        struct exofs_io_state *ios;
        struct osd_attr attr;
        struct exofs_fcb *fcb;
        struct updatei_args *args;
        int ret;

        args = kzalloc(sizeof(*args), GFP_KERNEL);
        if (!args) {
                EXOFS_DBGMSG("Faild kzalloc of args\n");
                return -ENOMEM;
        }

        fcb = &args->fcb;

        fcb->i_mode = cpu_to_le16(inode->i_mode);
        fcb->i_uid = cpu_to_le32(inode->i_uid);
        fcb->i_gid = cpu_to_le32(inode->i_gid);
        fcb->i_links_count = cpu_to_le16(inode->i_nlink);
        fcb->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
        fcb->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
        fcb->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
        oi->i_commit_size = i_size_read(inode);
        fcb->i_size = cpu_to_le64(oi->i_commit_size);
        fcb->i_generation = cpu_to_le32(inode->i_generation);

        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
                if (old_valid_dev(inode->i_rdev)) {
                        fcb->i_data[0] =
                                cpu_to_le32(old_encode_dev(inode->i_rdev));
                        fcb->i_data[1] = 0;
                } else {
                        fcb->i_data[0] = 0;
                        fcb->i_data[1] =
                                cpu_to_le32(new_encode_dev(inode->i_rdev));
                        fcb->i_data[2] = 0;
                }
        } else
                memcpy(fcb->i_data, oi->i_data, sizeof(fcb->i_data));

        ret = exofs_get_io_state(&sbi->layout, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: exofs_get_io_state failed.\n", __func__);
                goto free_args;
        }

        attr = g_attr_inode_data;
        attr.val_ptr = fcb;
        ios->out_attr_len = 1;
        ios->out_attr = &attr;

        if (!obj_created(oi)) {
                EXOFS_DBGMSG("!obj_created\n");
                BUG_ON(!obj_2bcreated(oi));
                wait_event(oi->i_wq, obj_created(oi));
                EXOFS_DBGMSG("wait_event done\n");
        }

        if (!do_sync) {
                args->sbi = sbi;
                ios->done = updatei_done;
                ios->private = args;
        }

        ret = exofs_oi_write(oi, ios);
        if (!do_sync && !ret) {
                atomic_inc(&sbi->s_curr_pending);
                goto out; /* deallocation in updatei_done */
        }

        exofs_put_io_state(ios);
free_args:
        kfree(args);
out:
        EXOFS_DBGMSG("(0x%lx) do_sync=%d ret=>%d\n",
                     inode->i_ino, do_sync, ret);
        return ret;
}

int exofs_write_inode(struct inode *inode, int wait)
{
        return exofs_update_inode(inode, wait);
}

/*
 * Callback function from exofs_delete_inode() - don't have much cleaning up to
 * do.
 */
static void delete_done(struct exofs_io_state *ios, void *p)
{
        struct exofs_sb_info *sbi = p;

        exofs_put_io_state(ios);

        atomic_dec(&sbi->s_curr_pending);
}

/*
 * Called when the refcount of an inode reaches zero.  We remove the object
 * from the OSD here.  We make sure the object was created before we try and
 * delete it.
 */
void exofs_delete_inode(struct inode *inode)
{
        struct exofs_i_info *oi = exofs_i(inode);
        struct super_block *sb = inode->i_sb;
        struct exofs_sb_info *sbi = sb->s_fs_info;
        struct exofs_io_state *ios;
        int ret;

        truncate_inode_pages(&inode->i_data, 0);

        if (is_bad_inode(inode))
                goto no_delete;

        mark_inode_dirty(inode);
        exofs_update_inode(inode, inode_needs_sync(inode));

        inode->i_size = 0;
        if (inode->i_blocks)
                exofs_truncate(inode);

        clear_inode(inode);

        ret = exofs_get_io_state(&sbi->layout, &ios);
        if (unlikely(ret)) {
                EXOFS_ERR("%s: exofs_get_io_state failed\n", __func__);
                return;
        }

        /* if we are deleting an obj that hasn't been created yet, wait */
        if (!obj_created(oi)) {
                BUG_ON(!obj_2bcreated(oi));
                wait_event(oi->i_wq, obj_created(oi));
        }

        ios->obj.id = exofs_oi_objno(oi);
        ios->done = delete_done;
        ios->private = sbi;
        ios->cred = oi->i_cred;
        ret = exofs_sbi_remove(ios);
        if (ret) {
                EXOFS_ERR("%s: exofs_sbi_remove failed\n", __func__);
                exofs_put_io_state(ios);
                return;
        }
        atomic_inc(&sbi->s_curr_pending);

        return;

no_delete:
        clear_inode(inode);
}