linux-stable.git/drivers/staging/zram, branch linux-3.1.y

Staging: zram: Fix kunmapping order

2011-07-18T20:22:52+00:00

This patch fixes the unmapping order of KM_USER0/1 in
handle_uncompressed_page() and zram_read() so that kmap()/kunmap() calls
are correctly nested.

Reported-by: Nitin Gupta 
Signed-off-by: Jerome Marchand 
Reviewed-by: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman

Staging: zram: Replace mutex lock by a R/W semaphore

2011-07-05T17:07:13+00:00

Currently, nothing protects zram table from concurrent access.
For instance, ZRAM_UNCOMPRESSED bit can be cleared by zram_free_page()
called from a concurrent write between the time ZRAM_UNCOMPRESSED has
been set and the time it is tested to unmap KM_USER0 in
zram_bvec_write(). This ultimately leads to kernel panic.

Also, a read request can occurs when the page has been freed by a
running write request and before it has been updated, leading to
zero filled block being incorrectly read and "Read before write"
error message.

This patch replace the current mutex by a rw_semaphore. It extends
the protection to zram table (currently, only compression buffers are
protected) and read requests (currently, only write requests are
protected).

Signed-off-by: Jerome Marchand 
Signed-off-by: Greg Kroah-Hartman

Staging: zram: allow partial page operations

2011-07-05T17:07:13+00:00

Commit 7b19b8d45b216ff3186f066b31937bdbde066f08 (zram: Prevent overflow
in logical block size) introduced ZRAM_LOGICAL_BLOCK_SIZE constant to
prevent overflow of logical block size on 64k page kernel.
However, the current implementation of zram only allow operation on block
of the same size as a page. That makes theorically legit 4k requests fail
on 64k page kernel.

This patch makes zram allow operation on partial pages. Basically, it
means we still do operations on full pages internally, but only copy the
relevent segments from/to the user memory.

Signed-off-by: Jerome Marchand 
Signed-off-by: Greg Kroah-Hartman

Staging: zram: Refactor zram_read/write() functions

2011-07-05T17:07:13+00:00

This patch refactor the code of zram_read/write() functions. It does
not removes a lot of duplicate code alone, but is mostly a helper for
the third patch of this series (Staging: zram: allow partial page
operations).

Signed-off-by: Jerome Marchand 
Signed-off-by: Greg Kroah-Hartman

Staging: zram: Remove useless offset calculation in handle_uncompressed_page()

2011-07-05T17:07:13+00:00

The offset of uncompressed page is always zero: handle_uncompressed_page()
doesn't have to care about it.

Signed-off-by: Jerome Marchand 
Signed-off-by: Greg Kroah-Hartman

staging: Allow sharing xvmalloc for zram and zcache

2011-02-23T22:02:56+00:00

Both zram and zcache use xvmalloc allocator. If xvmalloc
is compiled separately for both of them, we will get linker
error if they are both selected as "built-in". We can also
get linker error regarding missing xvmalloc symbols if zram
is not built.

So, we now compile xvmalloc separately and export its symbols
which are then used by both of zram and zcache.

Signed-off-by: Nitin Gupta 
Acked-by: Randy Dunlap 
Signed-off-by: Greg Kroah-Hartman

Staging: zram: initialize device on first read

2011-02-18T21:26:12+00:00

Currently the device is initialized when first write is done to the
device. Any read attempt before the first write would fail, including
"hidden" read the user may not know about (as for example if he tries
to write a partial block).

This patch initializes the device on first request, whether read or
write.

Signed-off-by: Jerome Marchand 
Cc: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman

Merge 2.6.38-rc5 into staging-next

2011-02-18T20:11:27+00:00

This is to resolve a merge conflict with:
	drivers/staging/zram/zram_drv.c
as pointed out by Stephen Rothwell

Cc: Stephen Rothwell 
Cc: Nitin Gupta 
Cc: Robert Jennings 
Signed-off-by: Greg Kroah-Hartman

staging: zram: fix data corruption issue

2011-02-09T19:39:51+00:00

In zram_read() and zram_write() we were not incrementing the
index number and thus were reading/writing values from/to
incorrect sectors on zram disk, resulting in data corruption.

Signed-off-by: Nitin Gupta 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

zram/xvmalloc: combine duplicate block delete code

2011-02-04T21:29:12+00:00

This patch eliminates duplicate code.  The remove_block_head function
is a special case of remove_block which can be contained in remove_block
without confusion.

The portion of code in remove_block_head which was noted as "DEBUG ONLY"
is now mandatory.  Doing this provides consistent management of the double
linked list of blocks under a freelist and makes this consolidation
of delete block code safe.  The first and last blocks will have NULL
pointers in their previous and next page pointers respectively.

Additionally, any time a block is removed from a free list the next and
previous pointers will be set to NULL to avoid misuse outside xvmalloc.

Signed-off-by: Robert Jennings 
Reviewed-by: Pekka Enberg 
Acked-by: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman