[Ocfs2-devel] [PATCH 01/15] ocfs2: move nonsparse hole-filling
into ocfs2_write_begin()
Joel Becker
Joel.Becker at oracle.com
Thu Sep 20 11:22:19 PDT 2007
On Tue, Aug 28, 2007 at 05:13:23PM -0700, Mark Fasheh wrote:
> By doing this, we can remove any higher level logic which has to have
> knowledge of btree functionality - any callers of ocfs2_write_begin() can
> now expect it to do anything necessary to prepare the inode for new data.
I like the way extend_file gains smarts - it knows what it's doing. I
also like the clean comments about how we prevent cluster and local
concurrent access.
Signed-off-by: Joel Becker <joel.becker at oracle.com>
>
> Signed-off-by: Mark Fasheh <mark.fasheh at oracle.com>
> ---
> fs/ocfs2/aops.c | 40 +++++++++-
> fs/ocfs2/file.c | 217 ++++++++++++++++++++-----------------------------------
> fs/ocfs2/file.h | 2 +
> 3 files changed, 115 insertions(+), 144 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 460d440..97394c5 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -301,12 +301,8 @@ int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
> {
> int ret;
>
> - down_read(&OCFS2_I(inode)->ip_alloc_sem);
> -
> ret = block_prepare_write(page, from, to, ocfs2_get_block);
>
> - up_read(&OCFS2_I(inode)->ip_alloc_sem);
> -
> return ret;
> }
>
> @@ -1353,6 +1349,36 @@ out:
> return ret;
> }
>
> +/*
> + * This function only does anything for file systems which can't
> + * handle sparse files.
> + *
> + * What we want to do here is fill in any hole between the current end
> + * of allocation and the end of our write. That way the rest of the
> + * write path can treat it as an non-allocating write, which has no
> + * special case code for sparse/nonsparse files.
> + */
> +static int ocfs2_expand_nonsparse_inode(struct inode *inode, loff_t pos,
> + unsigned len,
> + struct ocfs2_write_ctxt *wc)
> +{
> + int ret;
> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> + loff_t newsize = pos + len;
> +
> + if (ocfs2_sparse_alloc(osb))
> + return 0;
> +
> + if (newsize <= i_size_read(inode))
> + return 0;
> +
> + ret = ocfs2_extend_no_holes(inode, newsize, newsize - len);
> + if (ret)
> + mlog_errno(ret);
> +
> + return ret;
> +}
> +
> int ocfs2_write_begin_nolock(struct address_space *mapping,
> loff_t pos, unsigned len, unsigned flags,
> struct page **pagep, void **fsdata,
> @@ -1374,6 +1400,12 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
> return ret;
> }
>
> + ret = ocfs2_expand_nonsparse_inode(inode, pos, len, wc);
> + if (ret) {
> + mlog_errno(ret);
> + goto out;
> + }
> +
> ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
> &extents_to_split);
> if (ret) {
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 4ffa715..429ebcb 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -780,25 +780,6 @@ leave:
> return status;
> }
>
> -static int ocfs2_extend_allocation(struct inode *inode, u32 logical_start,
> - u32 clusters_to_add, int mark_unwritten)
> -{
> - int ret;
> -
> - /*
> - * The alloc sem blocks peope in read/write from reading our
> - * allocation until we're done changing it. We depend on
> - * i_mutex to block other extend/truncate calls while we're
> - * here.
> - */
> - down_write(&OCFS2_I(inode)->ip_alloc_sem);
> - ret = __ocfs2_extend_allocation(inode, logical_start, clusters_to_add,
> - mark_unwritten);
> - up_write(&OCFS2_I(inode)->ip_alloc_sem);
> -
> - return ret;
> -}
> -
> /* Some parts of this taken from generic_cont_expand, which turned out
> * to be too fragile to do exactly what we need without us having to
> * worry about recursive locking in ->prepare_write() and
> @@ -890,25 +871,47 @@ out:
> return ret;
> }
>
> -/*
> - * A tail_to_skip value > 0 indicates that we're being called from
> - * ocfs2_file_aio_write(). This has the following implications:
> - *
> - * - we don't want to update i_size
> - * - di_bh will be NULL, which is fine because it's only used in the
> - * case where we want to update i_size.
> - * - ocfs2_zero_extend() will then only be filling the hole created
> - * between i_size and the start of the write.
> - */
> +int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size, u64 zero_to)
> +{
> + int ret;
> + u32 clusters_to_add;
> + struct ocfs2_inode_info *oi = OCFS2_I(inode);
> +
> + clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size);
> + if (clusters_to_add < oi->ip_clusters)
> + clusters_to_add = 0;
> + else
> + clusters_to_add -= oi->ip_clusters;
> +
> + if (clusters_to_add) {
> + ret = __ocfs2_extend_allocation(inode, oi->ip_clusters,
> + clusters_to_add, 0);
> + if (ret) {
> + mlog_errno(ret);
> + goto out;
> + }
> + }
> +
> + /*
> + * Call this even if we don't add any clusters to the tree. We
> + * still need to zero the area between the old i_size and the
> + * new i_size.
> + */
> + ret = ocfs2_zero_extend(inode, zero_to);
> + if (ret < 0)
> + mlog_errno(ret);
> +
> +out:
> + return ret;
> +}
> +
> static int ocfs2_extend_file(struct inode *inode,
> struct buffer_head *di_bh,
> - u64 new_i_size,
> - size_t tail_to_skip)
> + u64 new_i_size)
> {
> int ret = 0;
> - u32 clusters_to_add = 0;
>
> - BUG_ON(!tail_to_skip && !di_bh);
> + BUG_ON(!di_bh);
>
> /* setattr sometimes calls us like this. */
> if (new_i_size == 0)
> @@ -918,13 +921,8 @@ static int ocfs2_extend_file(struct inode *inode,
> goto out;
> BUG_ON(new_i_size < i_size_read(inode));
>
> - if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
> - BUG_ON(tail_to_skip != 0);
> + if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
> goto out_update_size;
> - }
> -
> - clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size) -
> - OCFS2_I(inode)->ip_clusters;
>
> /*
> * protect the pages that ocfs2_zero_extend is going to be
> @@ -939,35 +937,25 @@ static int ocfs2_extend_file(struct inode *inode,
> goto out;
> }
>
> - if (clusters_to_add) {
> - ret = ocfs2_extend_allocation(inode,
> - OCFS2_I(inode)->ip_clusters,
> - clusters_to_add, 0);
> - if (ret < 0) {
> - mlog_errno(ret);
> - goto out_unlock;
> - }
> - }
> -
> /*
> - * Call this even if we don't add any clusters to the tree. We
> - * still need to zero the area between the old i_size and the
> - * new i_size.
> + * The alloc sem blocks people in read/write from reading our
> + * allocation until we're done changing it. We depend on
> + * i_mutex to block other extend/truncate calls while we're
> + * here.
> */
> - ret = ocfs2_zero_extend(inode, (u64)new_i_size - tail_to_skip);
> + down_write(&OCFS2_I(inode)->ip_alloc_sem);
> + ret = ocfs2_extend_no_holes(inode, new_i_size, new_i_size);
> + up_write(&OCFS2_I(inode)->ip_alloc_sem);
> +
> if (ret < 0) {
> mlog_errno(ret);
> goto out_unlock;
> }
>
> out_update_size:
> - if (!tail_to_skip) {
> - /* We're being called from ocfs2_setattr() which wants
> - * us to update i_size */
> - ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
> - if (ret < 0)
> - mlog_errno(ret);
> - }
> + ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
> + if (ret < 0)
> + mlog_errno(ret);
>
> out_unlock:
> if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
> @@ -1036,7 +1024,7 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
> if (i_size_read(inode) > attr->ia_size)
> status = ocfs2_truncate_file(inode, bh, attr->ia_size);
> else
> - status = ocfs2_extend_file(inode, bh, attr->ia_size, 0);
> + status = ocfs2_extend_file(inode, bh, attr->ia_size);
> if (status < 0) {
> if (status != -ENOSPC)
> mlog_errno(status);
> @@ -1714,15 +1702,13 @@ static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
> int appending,
> int *direct_io)
> {
> - int ret = 0, meta_level = appending;
> + int ret = 0, meta_level = 0;
> struct inode *inode = dentry->d_inode;
> - u32 clusters;
> - loff_t newsize, saved_pos;
> + loff_t saved_pos, end;
>
> /*
> - * We sample i_size under a read level meta lock to see if our write
> - * is extending the file, if it is we back off and get a write level
> - * meta lock.
> + * We start with a read level meta lock and only jump to an ex
> + * if we need to make modifications here.
> */
> for(;;) {
> ret = ocfs2_meta_lock(inode, NULL, meta_level);
> @@ -1764,87 +1750,38 @@ static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
> saved_pos = *ppos;
> }
>
> - if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
> - loff_t end = saved_pos + count;
> -
> - /*
> - * Skip the O_DIRECT checks if we don't need
> - * them.
> - */
> - if (!direct_io || !(*direct_io))
> - break;
> -
> - /*
> - * Allowing concurrent direct writes means
> - * i_size changes wouldn't be synchronized, so
> - * one node could wind up truncating another
> - * nodes writes.
> - */
> - if (end > i_size_read(inode)) {
> - *direct_io = 0;
> - break;
> - }
> + end = saved_pos + count;
>
> - /*
> - * We don't fill holes during direct io, so
> - * check for them here. If any are found, the
> - * caller will have to retake some cluster
> - * locks and initiate the io as buffered.
> - */
> - ret = ocfs2_check_range_for_holes(inode, saved_pos,
> - count);
> - if (ret == 1) {
> - *direct_io = 0;
> - ret = 0;
> - } else if (ret < 0)
> - mlog_errno(ret);
> + /*
> + * Skip the O_DIRECT checks if we don't need
> + * them.
> + */
> + if (!direct_io || !(*direct_io))
> break;
> - }
>
> /*
> - * The rest of this loop is concerned with legacy file
> - * systems which don't support sparse files.
> + * Allowing concurrent direct writes means
> + * i_size changes wouldn't be synchronized, so
> + * one node could wind up truncating another
> + * nodes writes.
> */
> -
> - newsize = count + saved_pos;
> -
> - mlog(0, "pos=%lld newsize=%lld cursize=%lld\n",
> - (long long) saved_pos, (long long) newsize,
> - (long long) i_size_read(inode));
> -
> - /* No need for a higher level metadata lock if we're
> - * never going past i_size. */
> - if (newsize <= i_size_read(inode))
> + if (end > i_size_read(inode)) {
> + *direct_io = 0;
> break;
> -
> - if (meta_level == 0) {
> - ocfs2_meta_unlock(inode, meta_level);
> - meta_level = 1;
> - continue;
> }
>
> - spin_lock(&OCFS2_I(inode)->ip_lock);
> - clusters = ocfs2_clusters_for_bytes(inode->i_sb, newsize) -
> - OCFS2_I(inode)->ip_clusters;
> - spin_unlock(&OCFS2_I(inode)->ip_lock);
> -
> - mlog(0, "Writing at EOF, may need more allocation: "
> - "i_size = %lld, newsize = %lld, need %u clusters\n",
> - (long long) i_size_read(inode), (long long) newsize,
> - clusters);
> -
> - /* We only want to continue the rest of this loop if
> - * our extend will actually require more
> - * allocation. */
> - if (!clusters)
> - break;
> -
> - ret = ocfs2_extend_file(inode, NULL, newsize, count);
> - if (ret < 0) {
> - if (ret != -ENOSPC)
> - mlog_errno(ret);
> - goto out_unlock;
> - }
> + /*
> + * We don't fill holes during direct io, so
> + * check for them here. If any are found, the
> + * caller will have to retake some cluster
> + * locks and initiate the io as buffered.
> + */
> + ret = ocfs2_check_range_for_holes(inode, saved_pos, count);
> + if (ret == 1) {
> + *direct_io = 0;
> + ret = 0;
> + } else if (ret < 0)
> + mlog_errno(ret);
> break;
> }
>
> diff --git a/fs/ocfs2/file.h b/fs/ocfs2/file.h
> index 36fe27f..066f14a 100644
> --- a/fs/ocfs2/file.h
> +++ b/fs/ocfs2/file.h
> @@ -47,6 +47,8 @@ int ocfs2_do_extend_allocation(struct ocfs2_super *osb,
> struct ocfs2_alloc_context *data_ac,
> struct ocfs2_alloc_context *meta_ac,
> enum ocfs2_alloc_restarted *reason_ret);
> +int ocfs2_extend_no_holes(struct inode *inode, u64 new_i_size,
> + u64 zero_to);
> int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_dinode *di,
> u32 clusters_to_add, u32 extents_to_split,
> struct ocfs2_alloc_context **data_ac,
> --
> 1.5.0.6
>
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> http://oss.oracle.com/mailman/listinfo/ocfs2-devel
--
"People with narrow minds usually have broad tongues."
Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127
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