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    Subject[PATCH 15/42] ext4: Properly update i_disksize.
    Date
    From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

    With delayed allocation we use i_data_sem to update i_disksize. We need
    to update i_disksize only if the new size specified is greater than the
    current value and we need to make sure we don't race with other
    i_disksize update. With delayed allocation we will switch to the
    write_begin function for non-delayed allocation if we are low on free
    blocks. This means the write_begin function for non-delayed allocation
    also needs to use the same locking.

    We also need to check and update i_disksize even if the new size is less
    that inode.i_size because of delayed allocation.

    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
    ---
    fs/ext4/ext4.h | 11 ++++++++++
    fs/ext4/extents.c | 9 ++++---
    fs/ext4/inode.c | 54 +++++++++++++++++++++++++++++-----------------------
    3 files changed, 46 insertions(+), 28 deletions(-)

    diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
    index e13b9de..3e47b99 100644
    --- a/fs/ext4/ext4.h
    +++ b/fs/ext4/ext4.h
    @@ -1218,6 +1218,17 @@ do { \
    #define EXT4_FREEBLOCKS_WATERMARK 0
    #endif

    +static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
    +{
    + /*
    + * XXX: replace with spinlock if seen contended -bzzz
    + */
    + down_write(&EXT4_I(inode)->i_data_sem);
    + if (newsize > EXT4_I(inode)->i_disksize)
    + EXT4_I(inode)->i_disksize = newsize;
    + up_write(&EXT4_I(inode)->i_data_sem);
    + return ;
    +}

    /*
    * Inodes and files operations
    diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
    index 797f060..e8758df 100644
    --- a/fs/ext4/extents.c
    +++ b/fs/ext4/extents.c
    @@ -2878,10 +2878,11 @@ static void ext4_falloc_update_inode(struct inode *inode,
    * Update only when preallocation was requested beyond
    * the file size.
    */
    - if (!(mode & FALLOC_FL_KEEP_SIZE) &&
    - new_size > i_size_read(inode)) {
    - i_size_write(inode, new_size);
    - EXT4_I(inode)->i_disksize = new_size;
    + if (!(mode & FALLOC_FL_KEEP_SIZE)) {
    + if (new_size > i_size_read(inode))
    + i_size_write(inode, new_size);
    + if (new_size > EXT4_I(inode)->i_disksize)
    + ext4_update_i_disksize(inode, new_size);
    }

    }
    diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
    index 634f0bc..22fcbb6 100644
    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -1434,16 +1434,18 @@ static int ext4_ordered_write_end(struct file *file,
    ret = ext4_jbd2_file_inode(handle, inode);

    if (ret == 0) {
    - /*
    - * generic_write_end() will run mark_inode_dirty() if i_size
    - * changes. So let's piggyback the i_disksize mark_inode_dirty
    - * into that.
    - */
    loff_t new_i_size;

    new_i_size = pos + copied;
    - if (new_i_size > EXT4_I(inode)->i_disksize)
    - EXT4_I(inode)->i_disksize = new_i_size;
    + if (new_i_size > EXT4_I(inode)->i_disksize) {
    + ext4_update_i_disksize(inode, new_i_size);
    + /* We need to mark inode dirty even if
    + * new_i_size is less that inode->i_size
    + * bu greater than i_disksize.(hint delalloc)
    + */
    + ext4_mark_inode_dirty(handle, inode);
    + }
    +
    ret2 = generic_write_end(file, mapping, pos, len, copied,
    page, fsdata);
    copied = ret2;
    @@ -1468,8 +1470,14 @@ static int ext4_writeback_write_end(struct file *file,
    loff_t new_i_size;

    new_i_size = pos + copied;
    - if (new_i_size > EXT4_I(inode)->i_disksize)
    - EXT4_I(inode)->i_disksize = new_i_size;
    + if (new_i_size > EXT4_I(inode)->i_disksize) {
    + ext4_update_i_disksize(inode, new_i_size);
    + /* We need to mark inode dirty even if
    + * new_i_size is less that inode->i_size
    + * bu greater than i_disksize.(hint delalloc)
    + */
    + ext4_mark_inode_dirty(handle, inode);
    + }

    ret2 = generic_write_end(file, mapping, pos, len, copied,
    page, fsdata);
    @@ -1494,6 +1502,7 @@ static int ext4_journalled_write_end(struct file *file,
    int ret = 0, ret2;
    int partial = 0;
    unsigned from, to;
    + loff_t new_i_size;

    from = pos & (PAGE_CACHE_SIZE - 1);
    to = from + len;
    @@ -1508,11 +1517,12 @@ static int ext4_journalled_write_end(struct file *file,
    to, &partial, write_end_fn);
    if (!partial)
    SetPageUptodate(page);
    - if (pos+copied > inode->i_size)
    + new_i_size = pos + copied;
    + if (new_i_size > inode->i_size)
    i_size_write(inode, pos+copied);
    EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
    - if (inode->i_size > EXT4_I(inode)->i_disksize) {
    - EXT4_I(inode)->i_disksize = inode->i_size;
    + if (new_i_size > EXT4_I(inode)->i_disksize) {
    + ext4_update_i_disksize(inode, new_i_size);
    ret2 = ext4_mark_inode_dirty(handle, inode);
    if (!ret)
    ret = ret2;
    @@ -2227,18 +2237,9 @@ static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
    if (disksize > i_size_read(inode))
    disksize = i_size_read(inode);
    if (disksize > EXT4_I(inode)->i_disksize) {
    - /*
    - * XXX: replace with spinlock if seen contended -bzzz
    - */
    - down_write(&EXT4_I(inode)->i_data_sem);
    - if (disksize > EXT4_I(inode)->i_disksize)
    - EXT4_I(inode)->i_disksize = disksize;
    - up_write(&EXT4_I(inode)->i_data_sem);
    -
    - if (EXT4_I(inode)->i_disksize == disksize) {
    - ret = ext4_mark_inode_dirty(handle, inode);
    - return ret;
    - }
    + ext4_update_i_disksize(inode, disksize);
    + ret = ext4_mark_inode_dirty(handle, inode);
    + return ret;
    }
    ret = 0;
    }
    @@ -2654,6 +2655,11 @@ static int ext4_da_write_end(struct file *file,
    EXT4_I(inode)->i_disksize = new_i_size;
    }
    up_write(&EXT4_I(inode)->i_data_sem);
    + /* We need to mark inode dirty even if
    + * new_i_size is less that inode->i_size
    + * bu greater than i_disksize.(hint delalloc)
    + */
    + ext4_mark_inode_dirty(handle, inode);
    }
    }
    ret2 = generic_write_end(file, mapping, pos, len, copied,
    --
    1.5.6.1.205.ge2c7.dirty


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