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gfs2: Improve mmap write vs. punch_hole consistency 

When punching a hole in a file, use filemap_write_and_wait_range to
write back any dirty pages in the range of the hole.  As a side effect,
if the hole isn't page aligned, this marks unaligned pages at the
beginning and the end of the hole read-only.  This is required when the
block size is smaller than the page size: when those pages are written
to again after the hole punching, we must make sure that page_mkwrite is
called for those pages so that the page will be fully allocated and any
blocks turned into holes from the hole punching will be reallocated.
(If a page is writably mapped, page_mkwrite won't be called.)

Fixes xfstest generic/567.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2019-09-06 14:51:38 +01:00
parent 1a48049adb
commit 39c3a948ec
1 changed files with 9 additions and 2 deletions
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11
fs/gfs2/bmap.c
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@ -2440,8 +2440,16 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
struct inode *inode = file_inode(file);
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_sbd *sdp = GFS2_SB(inode);
unsigned int blocksize = i_blocksize(inode);
loff_t start, end;
int error;
start = round_down(offset, blocksize);
end = round_up(offset + length, blocksize) - 1;
error = filemap_write_and_wait_range(inode->i_mapping, start, end);
if (error)
return error;
if (gfs2_is_jdata(ip))
error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
GFS2_JTRUNC_REVOKES);
@ -2455,9 +2463,8 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
if (error)
goto out;
} else {
unsigned int start_off, end_len, blocksize;
unsigned int start_off, end_len;
blocksize = i_blocksize(inode);
start_off = offset & (blocksize - 1);
end_len = (offset + length) & (blocksize - 1);
if (start_off) {