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author | Eric Sandeen <sandeen@redhat.com> | 2007-12-18 00:20:10 (GMT) |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-12-18 03:28:17 (GMT) |
commit | 7a3f595cc8298df14a7c71b0d876bafd8e9e1cbf (patch) | |
tree | e2409b01431e230369182d3a450dcd9c2c6beb0a /fs/ecryptfs/read_write.c | |
parent | 8998979cc1f90da5a48b2e8a13833217c63f7c4a (diff) | |
download | linux-fsl-qoriq-7a3f595cc8298df14a7c71b0d876bafd8e9e1cbf.tar.xz |
ecryptfs: fix fsx data corruption problems
ecryptfs in 2.6.24-rc3 wasn't surviving fsx for me at all, dying after 4
ops. Generally, encountering problems with stale data and improperly
zeroed pages. An extending truncate + write for example would expose stale
data.
With the changes below I got to a million ops and beyond with all mmap ops
disabled - mmap still needs work. (A version of this patch on a RHEL5
kernel ran for over 110 million fsx ops)
I added a few comments as well, to the best of my understanding
as I read through the code.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Acked-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ecryptfs/read_write.c')
-rw-r--r-- | fs/ecryptfs/read_write.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 6b7474a..948f576 100644 --- a/fs/ecryptfs/read_write.c +++ b/fs/ecryptfs/read_write.c @@ -124,6 +124,10 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, loff_t pos; int rc = 0; + /* + * if we are writing beyond current size, then start pos + * at the current size - we'll fill in zeros from there. + */ if (offset > ecryptfs_file_size) pos = ecryptfs_file_size; else @@ -137,6 +141,7 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, if (num_bytes > total_remaining_bytes) num_bytes = total_remaining_bytes; if (pos < offset) { + /* remaining zeros to write, up to destination offset */ size_t total_remaining_zeros = (offset - pos); if (num_bytes > total_remaining_zeros) @@ -167,17 +172,27 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, } } ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); + + /* + * pos: where we're now writing, offset: where the request was + * If current pos is before request, we are filling zeros + * If we are at or beyond request, we are writing the *data* + * If we're in a fresh page beyond eof, zero it in either case + */ + if (pos < offset || !start_offset_in_page) { + /* We are extending past the previous end of the file. + * Fill in zero values to the end of the page */ + memset(((char *)ecryptfs_page_virt + + start_offset_in_page), 0, + PAGE_CACHE_SIZE - start_offset_in_page); + } + + /* pos >= offset, we are now writing the data request */ if (pos >= offset) { memcpy(((char *)ecryptfs_page_virt + start_offset_in_page), (data + data_offset), num_bytes); data_offset += num_bytes; - } else { - /* We are extending past the previous end of the file. - * Fill in zero values up to the start of where we - * will be writing data. */ - memset(((char *)ecryptfs_page_virt - + start_offset_in_page), 0, num_bytes); } kunmap_atomic(ecryptfs_page_virt, KM_USER0); flush_dcache_page(ecryptfs_page); |