ntfs: use direct pointer for inline data to avoid redundant allocation

Previously, NTFS used page allocation for IOMAP_INLINE to ensure that
the inline_data pointer was page-aligned, avoiding strict boundary checks
in the iomap core. Since the previous patch has removed the over-strict
PAGE_SIZE boundary check in iomap, NTFS can now safely point
iomap::inline_data directly to the MFT record.
This change eliminates redundant memory allocations and memcpy operations
in both read and write paths. It also simplifies the iomap_ops by removing
the need for a iomap_end callback that was previously used to free
the temporary page.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

diff --git a/fs/ntfs/iomap.c b/fs/ntfs/iomap.c
index dc7d8c893a699f99f8b39c4cced537e695129be0..52eecf5cb256aa9ecd2a77fde56f392420f1ab1d 100644 (file)
--- a/fs/ntfs/iomap.c
+++ b/fs/ntfs/iomap.c
@@ -89,7 +89,6 @@ static int ntfs_read_iomap_begin_resident(struct inode *inode, loff_t offset, lo
        u32 attr_len;
        int err = 0;
        char *kattr;
-       struct page *ipage;
 
        if (NInoAttr(ni))
                base_ni = ni->ext.base_ntfs_ino;
@@ -130,18 +129,10 @@ static int ntfs_read_iomap_begin_resident(struct inode *inode, loff_t offset, lo
 
        kattr = (u8 *)ctx->attr + le16_to_cpu(ctx->attr->data.resident.value_offset);
 
-       ipage = alloc_page(GFP_NOFS | __GFP_ZERO);
-       if (!ipage) {
-               err = -ENOMEM;
-               goto out;
-       }
-
-       memcpy(page_address(ipage), kattr, attr_len);
        iomap->type = IOMAP_INLINE;
-       iomap->inline_data = page_address(ipage);
+       iomap->inline_data = kattr;
        iomap->offset = 0;
        iomap->length = attr_len;
-       iomap->private = ipage;
 
 out:
        if (ctx)
@@ -286,21 +277,8 @@ static int ntfs_read_iomap_begin(struct inode *inode, loff_t offset, loff_t leng
                        srcmap, true);
 }
 
-static int ntfs_read_iomap_end(struct inode *inode, loff_t pos, loff_t length,
-               ssize_t written, unsigned int flags, struct iomap *iomap)
-{
-       if (iomap->type == IOMAP_INLINE) {
-               struct page *ipage = iomap->private;
-
-               put_page(ipage);
-       }
-
-       return written;
-}
-
 const struct iomap_ops ntfs_read_iomap_ops = {
        .iomap_begin = ntfs_read_iomap_begin,
-       .iomap_end = ntfs_read_iomap_end,
 };
 
 /*
@@ -358,7 +336,6 @@ static const struct iomap_ops ntfs_zero_read_iomap_ops = {
 
 const struct iomap_ops ntfs_seek_iomap_ops = {
        .iomap_begin = ntfs_seek_iomap_begin,
-       .iomap_end = ntfs_read_iomap_end,
 };
 
 int ntfs_dio_zero_range(struct inode *inode, loff_t offset, loff_t length)
@@ -659,7 +636,6 @@ static int ntfs_write_iomap_begin_resident(struct inode *inode, loff_t offset,
        u32 attr_len;
        int err = 0;
        char *kattr;
-       struct page *ipage;
 
        ctx = ntfs_attr_get_search_ctx(ni, NULL);
        if (!ctx) {
@@ -680,24 +656,18 @@ static int ntfs_write_iomap_begin_resident(struct inode *inode, loff_t offset,
        attr_len = le32_to_cpu(a->data.resident.value_length);
        kattr = (u8 *)a + le16_to_cpu(a->data.resident.value_offset);
 
-       ipage = alloc_page(GFP_NOFS | __GFP_ZERO);
-       if (!ipage) {
-               err = -ENOMEM;
-               goto out;
-       }
-
-       memcpy(page_address(ipage), kattr, attr_len);
        iomap->type = IOMAP_INLINE;
-       iomap->inline_data = page_address(ipage);
+       iomap->inline_data = kattr;
        iomap->offset = 0;
-       /* iomap requires there is only one INLINE_DATA extent */
        iomap->length = attr_len;
-       iomap->private = ipage;
 
 out:
        if (ctx)
                ntfs_attr_put_search_ctx(ctx);
-       mutex_unlock(&ni->mrec_lock);
+
+       if (err)
+               mutex_unlock(&ni->mrec_lock);
+
        return err;
 }
 
@@ -778,43 +748,10 @@ static int ntfs_write_iomap_end_resident(struct inode *inode, loff_t pos,
                                         unsigned int flags, struct iomap *iomap)
 {
        struct ntfs_inode *ni = NTFS_I(inode);
-       struct ntfs_attr_search_ctx *ctx;
-       u32 attr_len;
-       int err;
-       char *kattr;
-       struct page *ipage = iomap->private;
 
-       mutex_lock(&ni->mrec_lock);
-       ctx = ntfs_attr_get_search_ctx(ni, NULL);
-       if (!ctx) {
-               written = -ENOMEM;
-               goto err_out;
-       }
-
-       err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
-                              CASE_SENSITIVE, 0, NULL, 0, ctx);
-       if (err) {
-               if (err == -ENOENT)
-                       err = -EIO;
-               written = err;
-               goto err_out;
-       }
-
-       /* The total length of the attribute value. */
-       attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
-       if (pos >= attr_len || pos + written > attr_len)
-               goto err_out;
-
-       kattr = (u8 *)ctx->attr + le16_to_cpu(ctx->attr->data.resident.value_offset);
-       memcpy(kattr + pos, iomap_inline_data(iomap, pos), written);
-       mark_mft_record_dirty(ctx->ntfs_ino);
-err_out:
-       if (ctx)
-               ntfs_attr_put_search_ctx(ctx);
-       put_page(ipage);
+       mark_mft_record_dirty(ni);
        mutex_unlock(&ni->mrec_lock);
        return written;
-
 }
 
 static int ntfs_write_iomap_end(struct inode *inode, loff_t pos, loff_t length,