diff options
author | Michael Halcrow <mhalcrow@us.ibm.com> | 2007-05-23 20:58:15 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-24 03:14:15 (GMT) |
commit | 53a2731f9310a66beaf55677229ab067c85ce4fa (patch) | |
tree | 6166f49b9205541a96696f648217c606cc9d9a0a /fs/ecryptfs/mmap.c | |
parent | 4acb3e2f97f41cf9b53182b494384467d3ceb304 (diff) | |
download | linux-fsl-qoriq-53a2731f9310a66beaf55677229ab067c85ce4fa.tar.xz |
eCryptfs: delay writing 0's after llseek until write
Delay writing 0's out in eCryptfs after a seek past the end of the file
until data is actually written.
http://www.opengroup.org/onlinepubs/009695399/functions/lseek.html
``The lseek() function shall not, by itself, extend the size of a
file.''
Without this fix, applications that lseek() past the end of the file without
writing will experience unexpected behavior.
Signed-off-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/mmap.c')
-rw-r--r-- | fs/ecryptfs/mmap.c | 38 |
1 files changed, 35 insertions, 3 deletions
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 88ea669..55cec98 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -376,9 +376,31 @@ out: return 0; } +/** + * eCryptfs does not currently support holes. When writing after a + * seek past the end of the file, eCryptfs fills in 0's through to the + * current location. The code to fill in the 0's to all the + * intermediate pages calls ecryptfs_prepare_write_no_truncate(). + */ +static int +ecryptfs_prepare_write_no_truncate(struct file *file, struct page *page, + unsigned from, unsigned to) +{ + int rc = 0; + + if (from == 0 && to == PAGE_CACHE_SIZE) + goto out; /* If we are writing a full page, it will be + up to date. */ + if (!PageUptodate(page)) + rc = ecryptfs_do_readpage(file, page, page->index); +out: + return rc; +} + static int ecryptfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) { + loff_t pos; int rc = 0; if (from == 0 && to == PAGE_CACHE_SIZE) @@ -386,6 +408,16 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page, up to date. */ if (!PageUptodate(page)) rc = ecryptfs_do_readpage(file, page, page->index); + pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; + if (pos > i_size_read(page->mapping->host)) { + rc = ecryptfs_truncate(file->f_path.dentry, pos); + if (rc) { + printk(KERN_ERR "Error on attempt to " + "truncate to (higher) offset [%lld];" + " rc = [%d]\n", pos, rc); + goto out; + } + } out: return rc; } @@ -744,10 +776,10 @@ int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros) rc = PTR_ERR(tmp_page); goto out; } - rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros); - if (rc) { + if ((rc = ecryptfs_prepare_write_no_truncate(file, tmp_page, start, + (start + num_zeros)))) { ecryptfs_printk(KERN_ERR, "Error preparing to write zero's " - "to remainder of page at index [0x%.16x]\n", + "to page at index [0x%.16x]\n", index); page_cache_release(tmp_page); goto out; |