Re: [PATCH 1/2] BDI: Provide backing device capability information [try #3]
Andrew Morton <[EMAIL PROTECTED]> wrote: > > The attached patch replaces backing_dev_info::memory_backed with > > capabilitied bitmap. > > Looks sane to me, thanks. > > I hope you got all the conversions correct - breakage in the writeback > dirty accounting manifests in subtle ways. I'll double-check it. I think I got the logic as-was. This is quite easy to check just by looking at the patch. However, the as-was logic should possibly be changed to reflect the fact that the one control that there was has now been split into two. David - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/2] BDI: Provide backing device capability information [try #3]
Andrew Morton [EMAIL PROTECTED] wrote: The attached patch replaces backing_dev_info::memory_backed with capabilitied bitmap. Looks sane to me, thanks. I hope you got all the conversions correct - breakage in the writeback dirty accounting manifests in subtle ways. I'll double-check it. I think I got the logic as-was. This is quite easy to check just by looking at the patch. However, the as-was logic should possibly be changed to reflect the fact that the one control that there was has now been split into two. David - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/2] BDI: Provide backing device capability information [try #3]
David Howells <[EMAIL PROTECTED]> wrote: > > The attached patch replaces backing_dev_info::memory_backed with capabilitied > bitmap. Looks sane to me, thanks. I hope you got all the conversions correct - breakage in the writeback dirty accounting manifests in subtle ways. I'll double-check it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/2] BDI: Provide backing device capability information [try #3]
The attached patch replaces backing_dev_info::memory_backed with capabilitied
bitmap. The capabilities available include:
(*) BDI_CAP_NO_ACCT_DIRTY
Set if the pages associated with this backing device should not be
tracked by the dirty page accounting.
(*) BDI_CAP_NO_WRITEBACK
Set if dirty pages associated with this backing device should not have
writepage() or writepages() invoked upon them to clean them.
(*) Capability markers that indicate what a backing device is capable of
with regard to memory mapping facilities. These flags indicate whether a
device can be mapped directly, whether it can be copied for a mapping,
and whether direct mappings can be read, written and/or executed. This
information is primarily aimed at improving no-MMU private mapping
support.
The patch also provides convenience functions for determining the dirty-page
capabilities available on backing devices directly or on the backing devices
associated with a mapping. These are provided to keep line length down when
checking for the capabilities.
Signed-Off-By: David Howells <[EMAIL PROTECTED]>
---
diff -uNrp /warthog/kernels/linux-2.6.11-rc4/include/linux/backing-dev.h
linux-2.6.11-rc4-memback/include/linux/backing-dev.h
--- /warthog/kernels/linux-2.6.11-rc4/include/linux/backing-dev.h
2004-06-18 13:44:05.0 +0100
+++ linux-2.6.11-rc4-memback/include/linux/backing-dev.h2005-03-08
11:03:45.0 +
@@ -25,13 +25,39 @@ typedef int (congested_fn)(void *, int);
struct backing_dev_info {
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state;/* Always use atomic bitops on this */
- int memory_backed; /* Cannot clean pages with writepage */
+ unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
void *unplug_io_data;
};
+
+/*
+ * Flags in backing_dev_info::capability
+ * - The first two flags control whether dirty pages will contribute to the
+ * VM's accounting and whether writepages() should be called for dirty pages
+ * (something that would not, for example, be appropriate for ramfs)
+ * - These flags let !MMU mmap() govern direct device mapping vs immediate
+ * copying more easily for MAP_PRIVATE, especially for ROM filesystems
+ */
+#define BDI_CAP_NO_ACCT_DIRTY 0x0001 /* Dirty pages shouldn't
contribute to accounting */
+#define BDI_CAP_NO_WRITEBACK 0x0002 /* Don't write pages back */
+#define BDI_CAP_MAP_COPY 0x0004 /* Copy can be mapped
(MAP_PRIVATE) */
+#define BDI_CAP_MAP_DIRECT 0x0008 /* Can be mapped directly
(MAP_SHARED) */
+#define BDI_CAP_READ_MAP 0x0010 /* Can be mapped for reading */
+#define BDI_CAP_WRITE_MAP 0x0020 /* Can be mapped for writing */
+#define BDI_CAP_EXEC_MAP 0x0040 /* Can be mapped for execution
*/
+#define BDI_CAP_VMFLAGS \
+ (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+
+#if defined(VM_MAYREAD) && \
+ (BDI_CAP_READ_MAP != VM_MAYREAD || \
+BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
+BDI_CAP_EXEC_MAP != VM_MAYEXEC)
+#error please change backing_dev_info::capabilities flags
+#endif
+
extern struct backing_dev_info default_backing_dev_info;
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
@@ -62,4 +88,17 @@ static inline int bdi_rw_congested(struc
(1 << BDI_write_congested));
}
+#define bdi_cap_writeback_dirty(bdi) \
+ (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
+
+#define bdi_cap_account_dirty(bdi) \
+ (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
+
+#define mapping_cap_writeback_dirty(mapping) \
+ bdi_cap_writeback_dirty((mapping)->backing_dev_info)
+
+#define mapping_cap_account_dirty(mapping) \
+ bdi_cap_account_dirty((mapping)->backing_dev_info)
+
+
#endif /* _LINUX_BACKING_DEV_H */
diff -uNrp /warthog/kernels/linux-2.6.11-rc4/drivers/block/ll_rw_blk.c
linux-2.6.11-rc4-memback/drivers/block/ll_rw_blk.c
--- /warthog/kernels/linux-2.6.11-rc4/drivers/block/ll_rw_blk.c 2005-02-14
12:18:23.0 +
+++ linux-2.6.11-rc4-memback/drivers/block/ll_rw_blk.c 2005-03-08
11:09:54.0 +
@@ -238,7 +238,7 @@ void blk_queue_make_request(request_queu
q->make_request_fn = mfn;
q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) /
PAGE_CACHE_SIZE;
q->backing_dev_info.state = 0;
- q->backing_dev_info.memory_backed = 0;
+ q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
blk_queue_max_sectors(q, MAX_SECTORS);
blk_queue_hardsect_size(q, 512);
blk_queue_dma_alignment(q, 511);
diff -uNrp
[PATCH 1/2] BDI: Provide backing device capability information [try #3]
The attached patch replaces backing_dev_info::memory_backed with capabilitied
bitmap. The capabilities available include:
(*) BDI_CAP_NO_ACCT_DIRTY
Set if the pages associated with this backing device should not be
tracked by the dirty page accounting.
(*) BDI_CAP_NO_WRITEBACK
Set if dirty pages associated with this backing device should not have
writepage() or writepages() invoked upon them to clean them.
(*) Capability markers that indicate what a backing device is capable of
with regard to memory mapping facilities. These flags indicate whether a
device can be mapped directly, whether it can be copied for a mapping,
and whether direct mappings can be read, written and/or executed. This
information is primarily aimed at improving no-MMU private mapping
support.
The patch also provides convenience functions for determining the dirty-page
capabilities available on backing devices directly or on the backing devices
associated with a mapping. These are provided to keep line length down when
checking for the capabilities.
Signed-Off-By: David Howells [EMAIL PROTECTED]
---
diff -uNrp /warthog/kernels/linux-2.6.11-rc4/include/linux/backing-dev.h
linux-2.6.11-rc4-memback/include/linux/backing-dev.h
--- /warthog/kernels/linux-2.6.11-rc4/include/linux/backing-dev.h
2004-06-18 13:44:05.0 +0100
+++ linux-2.6.11-rc4-memback/include/linux/backing-dev.h2005-03-08
11:03:45.0 +
@@ -25,13 +25,39 @@ typedef int (congested_fn)(void *, int);
struct backing_dev_info {
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state;/* Always use atomic bitops on this */
- int memory_backed; /* Cannot clean pages with writepage */
+ unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
void *unplug_io_data;
};
+
+/*
+ * Flags in backing_dev_info::capability
+ * - The first two flags control whether dirty pages will contribute to the
+ * VM's accounting and whether writepages() should be called for dirty pages
+ * (something that would not, for example, be appropriate for ramfs)
+ * - These flags let !MMU mmap() govern direct device mapping vs immediate
+ * copying more easily for MAP_PRIVATE, especially for ROM filesystems
+ */
+#define BDI_CAP_NO_ACCT_DIRTY 0x0001 /* Dirty pages shouldn't
contribute to accounting */
+#define BDI_CAP_NO_WRITEBACK 0x0002 /* Don't write pages back */
+#define BDI_CAP_MAP_COPY 0x0004 /* Copy can be mapped
(MAP_PRIVATE) */
+#define BDI_CAP_MAP_DIRECT 0x0008 /* Can be mapped directly
(MAP_SHARED) */
+#define BDI_CAP_READ_MAP 0x0010 /* Can be mapped for reading */
+#define BDI_CAP_WRITE_MAP 0x0020 /* Can be mapped for writing */
+#define BDI_CAP_EXEC_MAP 0x0040 /* Can be mapped for execution
*/
+#define BDI_CAP_VMFLAGS \
+ (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+
+#if defined(VM_MAYREAD) \
+ (BDI_CAP_READ_MAP != VM_MAYREAD || \
+BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
+BDI_CAP_EXEC_MAP != VM_MAYEXEC)
+#error please change backing_dev_info::capabilities flags
+#endif
+
extern struct backing_dev_info default_backing_dev_info;
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
@@ -62,4 +88,17 @@ static inline int bdi_rw_congested(struc
(1 BDI_write_congested));
}
+#define bdi_cap_writeback_dirty(bdi) \
+ (!((bdi)-capabilities BDI_CAP_NO_WRITEBACK))
+
+#define bdi_cap_account_dirty(bdi) \
+ (!((bdi)-capabilities BDI_CAP_NO_ACCT_DIRTY))
+
+#define mapping_cap_writeback_dirty(mapping) \
+ bdi_cap_writeback_dirty((mapping)-backing_dev_info)
+
+#define mapping_cap_account_dirty(mapping) \
+ bdi_cap_account_dirty((mapping)-backing_dev_info)
+
+
#endif /* _LINUX_BACKING_DEV_H */
diff -uNrp /warthog/kernels/linux-2.6.11-rc4/drivers/block/ll_rw_blk.c
linux-2.6.11-rc4-memback/drivers/block/ll_rw_blk.c
--- /warthog/kernels/linux-2.6.11-rc4/drivers/block/ll_rw_blk.c 2005-02-14
12:18:23.0 +
+++ linux-2.6.11-rc4-memback/drivers/block/ll_rw_blk.c 2005-03-08
11:09:54.0 +
@@ -238,7 +238,7 @@ void blk_queue_make_request(request_queu
q-make_request_fn = mfn;
q-backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) /
PAGE_CACHE_SIZE;
q-backing_dev_info.state = 0;
- q-backing_dev_info.memory_backed = 0;
+ q-backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
blk_queue_max_sectors(q, MAX_SECTORS);
blk_queue_hardsect_size(q, 512);
blk_queue_dma_alignment(q, 511);
diff -uNrp
Re: [PATCH 1/2] BDI: Provide backing device capability information [try #3]
David Howells [EMAIL PROTECTED] wrote: The attached patch replaces backing_dev_info::memory_backed with capabilitied bitmap. Looks sane to me, thanks. I hope you got all the conversions correct - breakage in the writeback dirty accounting manifests in subtle ways. I'll double-check it. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
