3e12dbbdbd
Both direct IO and DAX pass an offset and count into get_blocks that will overflow a s64 variable when an IO goes into the last supported block in a file (i.e. at offset 2^63 - 1FSB bytes). This can be seen from the tracing: xfs_get_blocks_alloc: [...] offset 0x7ffffffffffff000 count 4096 xfs_gbmap_direct: [...] offset 0x7ffffffffffff000 count 4096 xfs_gbmap_direct_none:[...] offset 0x7ffffffffffff000 count 4096 0x7ffffffffffff000 + 4096 = 0x8000000000000000, and hence that overflows the s64 offset and we fail to detect the need for a filesize update and an ioend is not allocated. This is *mostly* avoided for direct IO because such extending IOs occur with full block allocation, and so the "IS_UNWRITTEN()" check still evaluates as true and we get an ioend that way. However, doing single sector extending IOs to this last block will expose the fact that file size updates will not occur after the first allocating direct IO as the overflow will then be exposed. There is one further complexity: the DAX page fault path also exposes the same issue in block allocation. However, page faults cannot extend the file size, so in this case we want to allocate the block but do not want to allocate an ioend to enable file size update at IO completion. Hence we now need to distinguish between the direct IO patch allocation and dax fault path allocation to avoid leaking ioend structures. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
67 lines
2.4 KiB
C
67 lines
2.4 KiB
C
/*
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* Copyright (c) 2005-2006 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_AOPS_H__
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#define __XFS_AOPS_H__
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extern mempool_t *xfs_ioend_pool;
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/*
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* Types of I/O for bmap clustering and I/O completion tracking.
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*/
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enum {
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XFS_IO_DELALLOC, /* covers delalloc region */
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XFS_IO_UNWRITTEN, /* covers allocated but uninitialized data */
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XFS_IO_OVERWRITE, /* covers already allocated extent */
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};
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#define XFS_IO_TYPES \
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{ XFS_IO_DELALLOC, "delalloc" }, \
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{ XFS_IO_UNWRITTEN, "unwritten" }, \
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{ XFS_IO_OVERWRITE, "overwrite" }
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/*
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* xfs_ioend struct manages large extent writes for XFS.
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* It can manage several multi-page bio's at once.
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*/
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typedef struct xfs_ioend {
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struct xfs_ioend *io_list; /* next ioend in chain */
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unsigned int io_type; /* delalloc / unwritten */
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int io_error; /* I/O error code */
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atomic_t io_remaining; /* hold count */
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struct inode *io_inode; /* file being written to */
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struct buffer_head *io_buffer_head;/* buffer linked list head */
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struct buffer_head *io_buffer_tail;/* buffer linked list tail */
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size_t io_size; /* size of the extent */
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xfs_off_t io_offset; /* offset in the file */
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struct work_struct io_work; /* xfsdatad work queue */
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struct xfs_trans *io_append_trans;/* xact. for size update */
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} xfs_ioend_t;
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extern const struct address_space_operations xfs_address_space_operations;
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int xfs_get_blocks(struct inode *inode, sector_t offset,
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struct buffer_head *map_bh, int create);
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int xfs_get_blocks_direct(struct inode *inode, sector_t offset,
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struct buffer_head *map_bh, int create);
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int xfs_get_blocks_dax_fault(struct inode *inode, sector_t offset,
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struct buffer_head *map_bh, int create);
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void xfs_end_io_dax_write(struct buffer_head *bh, int uptodate);
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extern void xfs_count_page_state(struct page *, int *, int *);
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#endif /* __XFS_AOPS_H__ */
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